Remove dead token-based verification system

- Remove verificationsCache array and loadVerifications() function from verification.ts
- Remove verifyToken() and verifyTokenSync() functions (multi-replica unsafe, never used)
- Remove createVerification() function (stores unused data)
- Remove GET /verify route and verifyPage() helper function
- Remove loadVerifications() call from startup
- Remove createVerification() usage from signup route
- Update imports and test mocks to match removed functions
- Keep active 6-digit code system intact (createPendingVerification, verifyCode, etc.)

All 559 tests passing. The active verification system using pending_verifications
table and 6-digit codes continues to work normally.

src/__tests__/setup.ts

@@ -72,12 +72,9 @@ vi.mock("../services/browser.js", () => ({
 
 // Mock verification service
 vi.mock("../services/verification.js", () => ({
-  verifyToken: vi.fn().mockReturnValue({ status: "invalid" }),
-  loadVerifications: vi.fn().mockResolvedValue(undefined),
   createPendingVerification: vi.fn().mockResolvedValue({ email: "test@test.com", code: "123456" }),
   verifyCode: vi.fn().mockResolvedValue({ status: "ok" }),
   isEmailVerified: vi.fn().mockResolvedValue(false),
-  createVerification: vi.fn().mockResolvedValue({ email: "test@test.com", token: "tok", apiKey: "key", createdAt: "", verifiedAt: null }),
   getVerifiedApiKey: vi.fn().mockResolvedValue(null),
 }));