feat(plugins): Add toggle support with lazy daemon instantiation (#1407)

Add togglePlugin() function and IPC command to toggle plugin visibility,
particularly for slideout-capable daemon plugins like AI Assistant.

Implementation uses lazy instantiation for daemon plugins:
- Daemons remain uninstantiated on load (respecting lifecycle)
- First toggle() call instantiates the daemon on-demand
- Subsequent toggles use the existing instance
- Prevents duplicate instantiation while supporting toggle functionality

This approach preserves the fix from f9b9d986 (ensure daemon plugins
not instantiated twice) while enabling new toggle capabilities.

Changes:
- Add PluginService.togglePlugin() with lazy instantiation
- Add DMSShellIPC plugin.toggle() command
- Maintains compatibility with existing daemon plugins

quickshell/Services/PluginService.qml

@@ -556,6 +556,33 @@ Singleton {
         return loadPlugin(pluginId, true);
     }
 
+    function togglePlugin(pluginId) {
+        let instance = pluginInstances[pluginId];
+
+        // Lazy instantiate daemon plugins on first toggle
+        // This respects the daemon lifecycle (not instantiated on load)
+        // while supporting toggle functionality for slideout-capable daemons
+        if (!instance && pluginDaemonComponents[pluginId]) {
+            const comp = pluginDaemonComponents[pluginId];
+            const newInstance = comp.createObject(root, {
+                "pluginId": pluginId,
+                "pluginService": root
+            });
+            if (newInstance) {
+                const newInstances = Object.assign({}, pluginInstances);
+                newInstances[pluginId] = newInstance;
+                pluginInstances = newInstances;
+                instance = newInstance;
+            }
+        }
+
+        if (instance && typeof instance.toggle === "function") {
+            instance.toggle();
+            return true;
+        }
+        return false;
+    }
+
     function savePluginData(pluginId, key, value) {
         SettingsData.setPluginSetting(pluginId, key, value);
         pluginDataChanged(pluginId);