Release v0.0.12

ttlSeconds now requires a positive integer and verifies Redis supports expire.
TTL applies to both scoped vault hashes and the token index.
Added opt-in fallbackToMemory: true.
Memory fallback is continuously warmed, so values written before a Redis outage remain available.
Fallback supports get, getByToken, set, and entries.
In-memory fallback follows the configured TTL.
Default behavior remains fail-fast when fallback is disabled.
Added tests covering TTL, Redis outages, warm fallback, writes during outages, invalid TTL, and strict failure behavior.