feat: enforce per-use-case Redis read deadlines

[lan17]

Summary

• require an application-selected RedisConfig.readTimeoutMs and support static CachedOptions.redisReadTimeoutMs overrides
• enforce one monotonic core wait deadline around each shared semantic Redis read, with late-settlement consumption and a cooperative AbortSignal
• represent operational read failures explicitly, fail open to the source, and skip the post-fallback Redis write
• preserve safe local publication for untracked keys while suppressing tracked local publication when watermark safety was not established
• pass read cancellation to node-redis, preserve GLIDE's client-level timeout contract, and export RedisReadContext plus RedisReadTimeoutError
• document the v0.8 migration and extend packed-consumer, adapter, liveness, coalescing, publication, and performance coverage

Why

Redis fail-open behavior was rejection-driven, so a read promise that never settled retained the process flight and prevented the source fallback from starting. A rejected untracked read also proceeded to a Redis write after fallback, exposing one invocation to the unhealthy client twice. The core now bounds caller-visible read waiting while leaving underlying resource lifetime to finite client-native budgets.

Compatibility

This is a deliberate pre-1.0 configuration change: every Redis-enabled DialCache instance must now provide a positive finite readTimeoutMs. Custom one-argument DialCacheRedisClient.read(request) implementations remain structurally compatible because the new read context is optional.

Validation

• corepack pnpm check — typecheck, 266 unit tests with coverage, ESM/CJS build and declarations, packed-consumer checks
• corepack pnpm test:integration — 69 Redis 6.2, Valkey 8, and Redis Cluster cases
• corepack pnpm benchmark:request-local — default 50,000-iteration / 1,000-follower matrix; Redis fan-out asserted one semantic read, one deadline timer, and one timer clear
• corepack pnpm audit --prod --audit-level high — no known vulnerabilities
• git diff --check

Closes #38