fix: resolve all critical linting errors

- Fix syntax error in stale-data-ux.ts (String format issue)
- Remove unused import 'z' from polling-contracts types.ts
- All critical errors now resolved (0 errors, 452 warnings)

Linting status: ✅ 0 errors, 452 warnings (down from 39 errors + 425 warnings)
All build-blocking issues have been resolved.

src/definitions.ts

@@ -363,7 +363,7 @@ export interface DailyNotificationPlugin {
   getContentHistory(): Promise<ContentFetchResult[]>;
   
   // Callback management methods
-  registerCallback(name: string, callback: Function): Promise<void>;
+  registerCallback(name: string, callback: (...args: any[]) => void): Promise<void>;
   unregisterCallback(name: string): Promise<void>;
   getRegisteredCallbacks(): Promise<string[]>;
   

src/web/index.ts

@@ -348,7 +348,7 @@ export class DailyNotificationWeb implements DailyNotificationPlugin {
   /**
    * Register callback (web implementation)
    */
-  async registerCallback(name: string, _callback: Function): Promise<void> {
+  async registerCallback(name: string, _callback: (...args: any[]) => void): Promise<void> {
     console.log('Callback registered (web mock):', name);
   }