feat: Complete plugin lifecycle management with lazy loading and runtime reload

Major changes:
- Add unload() method to all plugins for proper cleanup (unregister commands/providers/LSP clients, destroy widgets, clear state)
- Implement lazy widget loading via "show" signal across all containers
- Add autoload: false manifest option for manual/conditional plugin loading
- Add Plugins UI with runtime load/unload toggle via Ctrl+Shift+p
- Implement controller unregistration system with proper signal disconnection
- Add new events: UnregisterCommandEvent, GetFilesEvent, GetSourceViewsEvent, TogglePluginsUiEvent
- Fix signal leaks by tracking and disconnecting handlers in widgets (search/replace, LSP manager, tabs, telescope, markdown preview)
- Add Save/Save As to tabs context menu
- Improve search/replace behavior (selection handling, focus management)
- Add telescope file initialization from existing loaded files
- Refactor plugin reload watcher to dynamically add/remove plugins on filesystem changes
- Add new plugins: file_history, extend_source_view_menu, godot_lsp_client
- Fix bug in prettify_json (undefined variable reference)

src/plugins/plugins_ui.py

@@ -0,0 +1,100 @@
+# Python imports
+
+# Lib imports
+import gi
+from gi.repository import Gtk
+
+# Application imports
+
+
+
+class PluginsUI(Gtk.Dialog):
+    def __init__(self):
+        super(PluginsUI, self).__init__()
+
+        self._setup_styling()
+        self._setup_signals()
+        self._subscribe_to_events()
+        self._load_widgets()
+
+
+    def _setup_styling(self):
+        header   = Gtk.HeaderBar()
+        self.ctx = self.get_style_context()
+        self.ctx.add_class("plugin-ui")
+
+        self.set_title("Plugins")
+        self.set_size_request(450, 530)
+        self.set_deletable(False)
+        self.set_skip_pager_hint(True)
+        self.set_skip_taskbar_hint(True)
+
+        header.set_title("Plugins")
+        self.set_titlebar(header)
+        header.show()
+
+        window = widget_registery.get_object("main-window")
+        self.set_transient_for(window)
+
+    def _setup_signals(self):
+        ...
+
+    def _subscribe_to_events(self):
+        ...
+
+    def _load_widgets(self):
+        widget_registery.expose_object("plugin-ui", self)
+
+        content_area  = self.get_content_area()
+        scrolled_win  = Gtk.ScrolledWindow()
+        viewport      = Gtk.Viewport()
+        self.list_box = Gtk.ListBox()
+
+        self.list_box.set_selection_mode( Gtk.SelectionMode.NONE )
+        scrolled_win.set_vexpand(True)
+
+        viewport.add(self.list_box)
+        scrolled_win.add(viewport)
+        content_area.add(scrolled_win)
+
+        scrolled_win.show_all()
+
+    def add_row(self, manifest_meta, callback: callable):
+        box         = Gtk.Box()
+        plugin_lbl  = Gtk.Label(label = manifest_meta.manifest.name)
+        author_lbl  = Gtk.Label(label = manifest_meta.manifest.author)
+        version_lbl = Gtk.Label(label = manifest_meta.manifest.version)
+        is_autoload = manifest_meta.manifest.autoload
+        toggle_bttn = Gtk.ToggleButton(label = "Unload" if is_autoload else "Load")
+
+        toggle_bttn.set_active(is_autoload)
+        plugin_lbl.set_hexpand(True)
+        box.set_hexpand(True)
+        version_lbl.set_margin_left(15)
+        version_lbl.set_margin_right(15)
+        toggle_bttn.set_size_request(120, -1)
+
+        toggle_bttn.toggle_id = \
+            toggle_bttn.connect("toggled", callback, manifest_meta)
+
+        box.add(plugin_lbl)
+        box.add(author_lbl)
+        box.add(version_lbl)
+        box.add(toggle_bttn)
+        box.manifest_meta = manifest_meta
+
+        box.show_all()
+        self.list_box.add(box)
+
+    def remove_row(self, manifest_meta):
+        for row in self.list_box.get_children():
+            child = row.get_children()[0]
+            if not child.manifest_meta == manifest_meta: continue
+
+            child.manifest_meta = None
+            toggle_bttn         = getattr(child, "toggle_bttn", None)
+            toggle_bttn.disconnect(toggle_bttn.toggle_id)
+
+            self.list_box.remove(row)
+            box.destroy()
+            break