C-2 (CRITICAL): JWT decode_token now validates aud, iss, iat, jti claims.
Tokens without these claims are rejected. Audience 'ss-tools-api' and
issuer 'ss-tools' prevent cross-service token reuse.
H-2 (HIGH): Server-side JWT revocation via token_blacklist table.
- New TokenBlacklist model (SHA-256 hash only, never raw token)
- blacklist_token() on logout — revokes current session
- is_token_blacklisted() check in get_current_user
- Expired entries auto-pruned via _prune_blacklist()
H-3 (HIGH): Encryption key auto-generation removed — crash-early instead.
Previously, ensure_encryption_key() would auto-generate a Fernet key
on first run and write it to .env. This made encrypted data unrecoverable
when the key changed between deployments. Now raises RuntimeError with
a clear command to generate the key explicitly.
Also: update orthogonal security test for crash-early behavior.