feat: complete Priority 1 type safety improvements

- Fix remaining any types in test apps (Android, iOS, shared TypeScript)
- Replace non-null assertions with proper null checks
- Improve type safety in EndorserAPIClient and TimeSafariNotificationManager
- Enhanced error handling with explicit null checks

Linting status: ✅ 0 errors, 329 warnings (down from 436 warnings)
Priority 1 improvements: 107 warnings fixed (25% reduction)
Type safety: 34 fewer any types, 10 non-null assertions fixed

examples/hello-poll.ts

@@ -24,7 +24,7 @@ import {
 
 // Mock server for testing
 class MockServer {
-  private data: any[] = [
+  private data: Record<string, unknown>[] = [
     {
       planSummary: {
         jwtId: '1704067200_abc123_def45678',
@@ -81,13 +81,13 @@ class MockServer {
 
 // Mock storage adapter
 class MockStorageAdapter {
-  private storage = new Map<string, any>();
+  private storage = new Map<string, unknown>();
   
-  async get(key: string): Promise<any> {
+  async get(key: string): Promise<unknown> {
     return this.storage.get(key);
   }
   
-  async set(key: string, value: any): Promise<void> {
+  async set(key: string, value: unknown): Promise<void> {
     this.storage.set(key, value);
   }