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/routes/signup.ts

@@ -1,7 +1,7 @@
 import { Router, Request, Response } from "express";
 import rateLimit from "express-rate-limit";
 import { createFreeKey } from "../services/keys.js";
-import { createVerification, createPendingVerification, verifyCode, isEmailVerified, getVerifiedApiKey } from "../services/verification.js";
+import { createPendingVerification, verifyCode, isEmailVerified, getVerifiedApiKey } from "../services/verification.js";
 import { sendVerificationEmail } from "../services/email.js";
 import logger from "../services/logger.js";
 
@@ -140,8 +140,6 @@ router.post("/verify", verifyLimiter, async (req: Request, res: Response) => {
   switch (result.status) {
     case "ok": {
       const keyInfo = await createFreeKey(cleanEmail);
-      const verification = await createVerification(cleanEmail, keyInfo.key);
-      verification.verifiedAt = new Date().toISOString();
 
       res.json({
         status: "verified",