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- Clean up unused imports, dead code, and outdated JSON server configs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/ui/markdown_preview/plugin.py

@@ -41,18 +41,14 @@ class Plugin(PluginCode):
     def load(self):
         separator_right  = self.request_ui_element("separator-right")
         markdown_preview.set_relative_to(separator_right)
-
-        event = Event_Factory.create_event("register_command",
-            command_name = "tggle_markdown_preview",
-            command      = Handler,
-            binding_mode = "released",
-            binding      = "<Shift><Control>m"
-        )
-
-        self.emit_to("source_views", event)
+        self._manage_signals("register_command")
 
     def unload(self):
-        event = Event_Factory.create_event("unregister_command",
+        self._manage_signals("unregister_command")
+        markdown_preview.destroy()
+
+    def _manage_signals(self, action: str):
+        event = Event_Factory.create_event(action,
             command_name = "tggle_markdown_preview",
             command      = Handler,
             binding_mode = "released",
@@ -61,8 +57,6 @@ class Plugin(PluginCode):
 
         self.emit_to("source_views", event)
 
-        markdown_preview.destroy()
-
     def run(self):
         ...