- Add POST /auth/verification-code endpoint to email a code
- Store codes in Redis and verify them during registration
- Send verification emails asynchronously via Thymeleaf
- Replace email_verified column with code-based verification
- Group dependencies into version catalogue bundles
Verify X-Hub-Signature-256 header using CryptoUtil.hmacSha256 from
onixbyte crypto-toolbox. Signature check is skipped when no secret is
configured. Uses MessageDigest.isEqual for constant-time comparison.