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/ui/tabs_bar/plugin.py

@@ -50,7 +50,14 @@ class Plugin(PluginCode):
     def unload(self):
         self.unregister_controller("tabs")
         self.tabs_controller.unload_tabs()
-        self.tabs_controller.tabs_widget.destroy()
+
+        tabs_widget  = self.tabs_controller.tabs_widget
+        viewport     = tabs_widget.get_parent()
+        scrolled_win = viewport.get_parent()
+
+        tabs_widget.destroy()
+        viewport.destroy()
+        scrolled_win.destroy()
 
         self.tabs_controller.tabs_widget = None
         self.tabs_controller             = None