cleanup: remove dead verification_token table and operations

[aspiers]

Problem

The verification_token table (packages/shared/src/db.ts:77-88) and its associated operations (createVerificationToken, getVerificationToken, markVerificationTokenUsed, incrementTokenAttempts, cleanupExpiredTokens, getVerificationTokenByCsrf) were part of the original custom OTP implementation.

This has been superseded by better-auth's emailOTP plugin, which uses its own verification table. No auth-service route code calls createVerificationToken or getVerificationToken anymore.

The cleanup timer in context.ts still runs cleanupExpiredTokens() on an empty table every 5 minutes.

Proposed Fix

1. Remove the verification_token table creation from the schema (or add a migration that drops it).
2. Remove the associated DB methods from EpdsDb.
3. Remove the cleanup timer call for cleanupExpiredTokens() (if it still exists).

Severity

Low — dead code increases audit surface but has no runtime impact.