chore: full implementation of code review recommendations (security, quality, tests)

lib/__tests__/auth.test.ts

@@ -4,6 +4,7 @@ import { describe, it, expect, vi } from 'vitest';
 vi.mock('@/lib/config', () => ({
   getConfig: () => ({
     immich: { apiKey: 'test-api-key-for-auth-tests' },
+    authSecret: 'test-auth-secret-32-chars-long-min',
     subpages: [
       {
         name: 'Private',