feat: Add minimal search functionality to gtm tool

This commit introduces a basic search feature with the following capabilities:
- Press '/' to enter search mode
- Type search query and press Enter to search
- Navigate through matches with 'n' and 'N'
- Highlight search matches in the file view
- Display search match count in status bar

gtm

@@ -139,6 +139,12 @@ class AppState:
     # Change navigation
     change_blocks: List[Tuple[int, int]] = field(default_factory=list)  # (start_line, end_line) of each change block
     current_change_idx: int = -1  # -1 means no change is selected
+    
+    # Search functionality
+    search_mode: bool = False
+    search_query: str = ""
+    search_matches: List[int] = field(default_factory=list)  # Line numbers of matches
+    current_match_idx: int = -1  # Index in search_matches
 
 # --- Actions (Controller) ---
 
@@ -355,6 +361,54 @@ def jump_to_prev_change(state: AppState) -> AppState:
         return replace(state, right_scroll_offset=new_scroll, current_change_idx=prev_idx)
     return state
 
+def perform_search(state: AppState) -> AppState:
+    """Search for the query in the file content and update matches."""
+    if not state.search_query:
+        return replace(state, search_matches=[], current_match_idx=-1)
+    
+    matches = []
+    query = state.search_query.lower()  # Case-insensitive search
+    
+    for i, line in enumerate(state.file_lines):
+        if query in line.lower():
+            matches.append(i)
+    
+    new_state = replace(state, search_matches=matches)
+    
+    # If we have matches, select the first one
+    if matches:
+        new_state = replace(new_state, current_match_idx=0)
+        # Scroll to the first match
+        new_state = replace(new_state, right_scroll_offset=max(0, matches[0] - 3))
+    else:
+        new_state = replace(new_state, current_match_idx=-1)
+    
+    return new_state
+
+def jump_to_next_match(state: AppState) -> AppState:
+    """Jump to the next search match."""
+    if not state.search_matches:
+        return state
+    
+    next_idx = (state.current_match_idx + 1) % len(state.search_matches)
+    new_state = replace(state, current_match_idx=next_idx)
+    
+    # Scroll to the match
+    match_line = state.search_matches[next_idx]
+    return replace(new_state, right_scroll_offset=max(0, match_line - 3))
+
+def jump_to_prev_match(state: AppState) -> AppState:
+    """Jump to the previous search match."""
+    if not state.search_matches:
+        return state
+    
+    prev_idx = (state.current_match_idx - 1) % len(state.search_matches)
+    new_state = replace(state, current_match_idx=prev_idx)
+    
+    # Scroll to the match
+    match_line = state.search_matches[prev_idx]
+    return replace(new_state, right_scroll_offset=max(0, match_line - 3))
+
 
 def draw_right_pane(stdscr, state):
     # If sidebar is hidden, right pane starts at column 0
@@ -411,6 +465,14 @@ def draw_right_pane(stdscr, state):
         content = line_info['content']
         line_num = line_info.get('line_num', 0)
         
+        # Check if this is a search match
+        is_search_match = False
+        is_current_match = False
+        if state.search_matches and line_num - 1 in state.search_matches:  # Adjust for 0-based indexing
+            match_idx = state.search_matches.index(line_num - 1)
+            is_search_match = True
+            is_current_match = (match_idx == state.current_match_idx)
+        
         # Draw line number if enabled
         if state.show_line_numbers:
             line_num_str = str(line_num).rjust(line_num_width - 1) + " "
@@ -437,6 +499,13 @@ def draw_right_pane(stdscr, state):
                 prefix = "  "
             attr = curses.A_NORMAL
         
+        # If this is a search match, override the attribute
+        if is_search_match:
+            if is_current_match:
+                attr = curses.A_REVERSE | curses.A_BOLD
+            else:
+                attr = curses.A_UNDERLINE
+        
         # Calculate available width for content
         content_start = right_start + len(prefix)
         available_width = right_width - len(prefix)
@@ -451,9 +520,42 @@ def draw_right_pane(stdscr, state):
             display_content = content
             if not state.wrap_lines and len(content) > available_width:
                 display_content = content[:available_width]
+            
+            # If this is a search match, highlight just the matching part
+            if is_search_match and state.search_query:
+                # Find all occurrences of the search query in the content (case-insensitive)
+                query = state.search_query.lower()
+                content_lower = display_content.lower()
+                pos = 0
+                while pos < len(content_lower):
+                    match_pos = content_lower.find(query, pos)
+                    if match_pos == -1:
+                        break
+                    
+                    # Draw the matching part with highlighting
+                    match_attr = attr
+                    if match_pos + len(query) <= len(display_content):
+                        # Draw text before match
+                        if match_pos > 0:
+                            stdscr.addnstr(display_row, content_start, display_content[:match_pos], match_pos)
+                        
+                        # Draw the match with highlighting
+                        match_text = display_content[match_pos:match_pos + len(query)]
+                        stdscr.addnstr(display_row, content_start + match_pos, match_text, len(query), match_attr)
+                        
+                        # Draw text after match
+                        if match_pos + len(query) < len(display_content):
+                            remaining_text = display_content[match_pos + len(query):]
+                            stdscr.addnstr(display_row, content_start + match_pos + len(query), 
+                                          remaining_text, len(remaining_text))
+                    
+                    pos = match_pos + 1
                 
-            stdscr.addnstr(display_row, content_start, display_content, available_width, attr)
+                display_row += 1
-            display_row += 1
+            else:
+                # Normal display without search highlighting
+                stdscr.addnstr(display_row, content_start, display_content, available_width, attr)
+                display_row += 1
         else:
             # Line needs wrapping and wrapping is enabled
             remaining = content
@@ -548,6 +650,39 @@ def draw_status_bars(stdscr, state):
     # We'll use height-1 for the single status bar
     visible_height = state.height - 1
     
+    # If in search mode, draw the search input field instead of the normal status bar
+    if state.search_mode:
+        # Fill the status bar with spaces
+        for x in range(state.width - 1):
+            try:
+                stdscr.addch(state.height - 1, x, ' ')
+            except curses.error:
+                pass
+        
+        # Draw search prompt
+        search_prompt = "Search: "
+        try:
+            stdscr.addstr(state.height - 1, 0, search_prompt)
+            
+            # Draw the search query
+            stdscr.addstr(state.height - 1, len(search_prompt), state.search_query)
+            
+            # Draw cursor at the end of the query
+            try:
+                stdscr.move(state.height - 1, len(search_prompt) + len(state.search_query))
+            except curses.error:
+                pass
+            
+            # If we have search results, show count
+            if state.search_matches:
+                match_info = f" [{state.current_match_idx + 1}/{len(state.search_matches)}]"
+                stdscr.addstr(state.height - 1, state.width - len(match_info) - 1, match_info)
+        except curses.error:
+            pass
+        
+        return
+    
+    # Normal status bar (not in search mode)
     # Get commit message for the selected commit
     commit_message = ""
     if state.commits and state.selected_commit_idx < len(state.commits):
@@ -564,7 +699,11 @@ def draw_status_bars(stdscr, state):
     if state.change_blocks and state.current_change_idx != -1:
         change_indicator = f"[Change {state.current_change_idx + 1}/{len(state.change_blocks)}] "
     
-    commit_message = wrap_indicator + change_indicator + commit_message
+    search_indicator = ""
+    if state.search_matches:
+        search_indicator = f"[Search {state.current_match_idx + 1}/{len(state.search_matches)}] "
+    
+    commit_message = wrap_indicator + change_indicator + search_indicator + commit_message
     
     # Status bar percentages
     if len(state.file_lines) > 0:
@@ -833,6 +972,24 @@ def handle_mouse_input(stdscr, state: AppState) -> AppState:
     return state
 
 def handle_keyboard_input(key, state: AppState) -> AppState:
+    # If in search mode, handle search input
+    if state.search_mode:
+        if key == 27:  # Escape key - exit search mode
+            return replace(state, search_mode=False)
+        elif key == 10 or key == 13:  # Enter key - perform search
+            new_state = perform_search(state)
+            return replace(new_state, search_mode=False)
+        elif key == 8 or key == 127 or key == curses.KEY_BACKSPACE:  # Backspace
+            if state.search_query:
+                return replace(state, search_query=state.search_query[:-1])
+        elif key == curses.KEY_DC:  # Delete key
+            if state.search_query:
+                return replace(state, search_query=state.search_query[:-1])
+        elif 32 <= key <= 126:  # Printable ASCII characters
+            return replace(state, search_query=state.search_query + chr(key))
+        return state
+    
+    # Normal mode key handling
     if key in [ord('q')]:
         return replace(state, should_exit=True)
     elif key == 27:  # Escape key
@@ -840,6 +997,8 @@ def handle_keyboard_input(key, state: AppState) -> AppState:
             return replace(state, is_selecting=False, selection_start_coord=None, selection_end_coord=None)
         else:
             return replace(state, should_exit=True)
+    elif key == ord('/'):  # Start search
+        return replace(state, search_mode=True, search_query="")
     elif key == ord('s'):
         return toggle_sidebar(state)
     elif key == ord('w'):
@@ -847,8 +1006,13 @@ def handle_keyboard_input(key, state: AppState) -> AppState:
     elif key == ord('l'):
         return replace(state, show_line_numbers=not state.show_line_numbers)
     elif key in [110, ord('n')]:  # ASCII code for 'n'
-        if state.show_whole_diff or state.show_additions or state.show_deletions:
+        if state.search_matches:
+            return jump_to_next_match(state)
+        elif state.show_whole_diff or state.show_additions or state.show_deletions:
             return jump_to_next_change(state)
+    elif key in [78, ord('N')]:  # ASCII code for 'N' (uppercase)
+        if state.search_matches:
+            return jump_to_prev_match(state)
     elif key in [112, ord('p')]:  # ASCII code for 'p'
         if state.show_whole_diff or state.show_additions or state.show_deletions:
             return jump_to_prev_change(state)
@@ -899,6 +1063,7 @@ def main(stdscr, filename, show_diff, show_add, show_del, mouse, wrap_lines=True
         curses.init_pair(5, curses.COLOR_GREEN, -1)  # Line numbers for added lines
         curses.init_pair(6, curses.COLOR_RED, -1)    # Line numbers for deleted lines
         curses.init_pair(7, curses.COLOR_BLUE, -1)   # Regular line numbers
+        curses.init_pair(8, curses.COLOR_BLACK, curses.COLOR_YELLOW)  # Search matches
 
     height, width = stdscr.getmaxyx()
     state = AppState(