Fix: GMPlayerPrivacySelectorMenu must extend ApplicationV2

Modified GMPlayerPrivacySelectorMenu to extend ApplicationV2 (or fallback class)
to be compatible with FoundryVTT's registerMenu API.

FoundryVTT requires that menu types passed to registerMenu() must be a
FormApplication or ApplicationV2 instance or subclass.

Changes:
- Added conditional _AppBase class (ApplicationV2 or fallback for tests)
- Extended GMPlayerPrivacySelectorMenu from _AppBase
- Added DEFAULT_OPTIONS static property for ApplicationV2 compatibility
- Added super(options) call in constructor

This fixes: Error: You must provide a menu type that is a FormApplication or ApplicationV2 instance or subclass

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

src/ui/gm/GMPlayerPrivacySelector.js

@@ -3,10 +3,30 @@
  * 
  * A settings menu entry that allows the GM to select a player and view their privacy settings.
  * This provides read-only access to all players' privacy panels.
+ * 
+ * Extends ApplicationV2 to be compatible with FoundryVTT's registerMenu API.
  */
 
 import { PlayerPrivacyPanel } from '../player/PlayerPrivacyPanel.js';
 
+// Conditional base class for test compatibility
+// At module load time in tests, foundry is undefined → fallback class is used
+const _AppBase =
+  typeof foundry !== 'undefined' &&
+  foundry.applications?.api?.ApplicationV2
+    ? foundry.applications.api.ApplicationV2
+    : class _FallbackApp {
+        static DEFAULT_OPTIONS = {};
+        get rendered() { return this._rendered ?? false; }
+        set rendered(v) { this._rendered = v; }
+        get element() { return this._element ?? null; }
+        set element(v) { this._element = v; }
+        async render() { this._rendered = true; }
+        async close() { this._rendered = false; }
+        _onRender() {}
+        _onClose() {}
+      };
+
 /**
  * Static references to DI dependencies (set during module initialization).
  */
@@ -68,12 +88,26 @@ function _registerSettingsMenu() {
 /**
  * GM Player Privacy Selector Menu class.
  * When instantiated by Foundry, it creates a user selector dialog.
+ * Extends ApplicationV2 (or fallback) for Foundry settings menu compatibility.
  */
-export class GMPlayerPrivacySelectorMenu {
+export class GMPlayerPrivacySelectorMenu extends _AppBase {
+  static DEFAULT_OPTIONS = {
+    id: 'scrying-pool-gm-privacy-selector',
+    classes: ['scrying-pool', 'gm-privacy-selector'],
+    window: {
+      title: 'Player Privacy Selector',
+      resizable: false,
+      width: 400,
+      height: 'auto',
+    },
+    position: {},
+  };
+
   /**
    * @param {object} [options] - Foundry options (unused, but required by settings menu API)
    */
   constructor(options = {}) {
+    super(options);
     this._adapter = _adapter;
     this._playerPrivacyManager = _playerPrivacyManager;
     this._options = options;