Every existing RedisCandidateIndex test runs against miniredis -- a
from-scratch Go reimplementation of the Redis command set, not real
Redis's own float64 score encoding, TTL/expiry, or RESP behavior.
Add an opt-in integration suite (mirroring postgres_integration_test.go's
pattern: //go:build integration, COSMIC_CLASH_REDIS_ADDR-gated) plus
scripts/run_redis_integration.sh against a disposable redis:7-alpine
container, covering:
- upsert/snapshot/remove against a real server
- a real TTL actually waited out (not miniredis's manual
FastForward), proving expiry really happens on the wire
- the documented 'Redis restart or lost keyspace' repair path
exercised against an actual FLUSHALL, not a simulated empty map,
including that the repair actually persists back to Redis (a
second snapshot reads it without a second durable-source call)
Verified stable across 3 runs with -race against a real container.