feat: improve LSP lifecycle, terminal widget, and code folding support

- LSP:
  - Add shutdown and exit request/notification handling
  - Send initialized notification after initialize response
  - Gracefully close clients with delayed shutdown via GLib timeout
  - Fix LSP WS server ↔ Godot LSP communication flow

- Terminal (VteWidget):
  - Switch to async spawn with full environment inheritance
  - Add PROMPT_COMMAND OSC7 support for cwd tracking
  - Improve UX: scrollback, no audible bell, auto scroll
  - Implement clipboard shortcuts, selection copy, middle-click paste
  - Track cwd changes and update UI label
  - Add proper signal wiring and cleanup on destroy

- Code folding:
  - Add fold support for JS, HTML, CSS, JSON, C, C++, Go
  - Reset fold state safely when AST or filetype is unavailable

- UI (Plugins dialog):
  - Improve dialog behavior (non-modal, centered, transient)
  - Add focus-out auto-hide and Ctrl+Shift+P shortcut

- Misc:
  - Add type hints in VTE widget
  - Update TODOs (remove completed items, add LSP comm fix)
  - Add terminal plugin scaffolding

plugins/code/ui/code_fold/plugin.py

@@ -25,15 +25,19 @@ class Plugin(PluginCode):
             self.view = event.view
 
             event = Event_Factory.create_event(
-                "get_file", buffer=self.view.get_buffer()
+                "get_file", buffer = self.view.get_buffer()
             )
             self.emit_to("files", event)
 
             file = event.response
 
             if not file: return
-            if file.ftype not in FOLD_NODES: return
-            if not hasattr(file, "ast"): return
+            if file.ftype not in FOLD_NODES:
+                self.view.fold_start_set = {}
+                return
+            if not hasattr(file, "ast"):
+                self.view.fold_start_set = {}
+                return
 
             buffer = file.buffer
             if not buffer.get_tag_table().lookup("invisible"):