Refactor LSP manager architecture and event + completion pipeline

- Replace legacy LSPManagerClient + LSPManagerUI with ClientManager and UIManager
- Remove WebsocketClient in favor of unified Websocket implementation
- Move LSP initialization config loading into centralized config module
- Update LSPClient to support dynamic socket, improved init params, and doc version tracking
- Introduce range-based didChange notifications and add implementation + references requests
- Expand LSPClientEvents to support implementation/references and structured range edits
- Simplify websocket response handling and normalize LSP response parsing flow
- Decouple UI from LSP manager core; UI now emits address/port for client creation
- Refactor completion provider pipeline:
  - Split TextChangedEvent into TextInsertedEvent and DeleteRangeEvent
  - Update ProviderResponseCacheBase and controller dispatch paths accordingly
- Improve SourceBuffer and SourceFile event tracking with delete-range support
- Update plugin system:
  - Centralize command/provider registration via helper methods
  - Add LSP commands: definition, references, implementation, toggle UI
- Enhance response handlers to support references and implementation hooks
- Improve Python LSP config (jedi completion, signatures, references enabled)
- Fix minor GTK lifecycle and buffer signal handling issues
- Clean up unused imports, dead code, and outdated JSON server configs

plugins/code/completers/snippets_completer/provider_response_cache.py

@@ -49,7 +49,10 @@ class ProviderResponseCache(ProviderResponseCacheBase):
     def process_file_save(self, event: Code_Event_Types.SavedFileEvent):
         ...
 
-    def process_file_change(self, event: Code_Event_Types.TextChangedEvent):
+    def process_file_text_inserted(self, event: Code_Event_Types.TextInsertedEvent):
+        ...
+
+    def process_file_delete_range(self, event: Code_Event_Types.DeleteRangeEvent):
         ...
 
     def filter(self, word: str) -> list[dict]: