🐛 fix(analytics): prevent multiple GTM initializations (#4174)

* feat(types): Add global window interface for Google Tag Manager

* refactor(Chat/Footer): Move GTM initialization to useEffect for better lifecycle management

* fix(hooks): add useEffect to initialize TagManager conditionally

client/src/common/types.ts

@@ -540,3 +540,9 @@ export type TVectorStore = {
 };
 
 export type TThread = { id: string; createdAt: string };
+
+declare global {
+  interface Window {
+    google_tag_manager?: unknown;
+  }
+}