feat: Complete plugin lifecycle management with lazy loading and runtime reload

Major changes:
- Add unload() method to all plugins for proper cleanup (unregister commands/providers/LSP clients, destroy widgets, clear state)
- Implement lazy widget loading via "show" signal across all containers
- Add autoload: false manifest option for manual/conditional plugin loading
- Add Plugins UI with runtime load/unload toggle via Ctrl+Shift+p
- Implement controller unregistration system with proper signal disconnection
- Add new events: UnregisterCommandEvent, GetFilesEvent, GetSourceViewsEvent, TogglePluginsUiEvent
- Fix signal leaks by tracking and disconnecting handlers in widgets (search/replace, LSP manager, tabs, telescope, markdown preview)
- Add Save/Save As to tabs context menu
- Improve search/replace behavior (selection handling, focus management)
- Add telescope file initialization from existing loaded files
- Refactor plugin reload watcher to dynamically add/remove plugins on filesystem changes
- Add new plugins: file_history, extend_source_view_menu, godot_lsp_client
- Fix bug in prettify_json (undefined variable reference)

plugins/code/ui/search_replace/mixins/search_replace_mixin.py

@@ -17,19 +17,17 @@ class SearchReplaceMixin(SearchMixin, ReplaceMixin):
         search_text = entry.get_text()
         buffer      = self.active_view.get_buffer()
 
-        if buffer.get_has_selection() and not search_text:
-            if not self.mode_bttn_box.in_selection:
-                start_itr, end_itr = buffer.get_selection_bounds()
+        if not buffer.get_has_selection() and search_text: return
+        if self.mode_bttn_box.in_selection: return
 
-                entry.set_text(
-                    buffer.get_text(
-                        start_itr,
-                        end_itr,
-                        include_hidden_chars = False
-                    )
-                )
-
-            return
+        start_itr, end_itr = buffer.get_selection_bounds()
+        entry.set_text(
+            buffer.get_text(
+                start_itr,
+                end_itr,
+                include_hidden_chars = False
+            )
+        )
 
     def _find_entry_search_change(self, entry):
         search_text        = entry.get_text()