Fix unload lifecycle, widget cleanup, and plugin removal handling

- Rename GodotHandler to GDScriptHandler in LSP client
- Fix unload() method naming in nanoesq_temp_buffer plugin
- Return manifest_meta in manifest_manager for manual launch plugins
- Properly destroy tabs_widget, viewport, and scrolled_win on unload
- Refactor plugin removal to search all manifest lists and fix cleanup order
- Fix widget reference in plugins_ui (use child instead of box)

plugins/code/commands/nanoesq_temp_buffer/plugin.py

@@ -23,7 +23,7 @@ class Plugin(PluginCode):
     def load(self):
         self._manage_signals("register_command")
 
-    def load(self):
+    def unload(self):
         self._manage_signals("unregister_command")
 
     def _manage_signals(self, action: str):