feat: remove flushAll from public API

[lan17]

Summary

Remove the database-wide flush capability from DialCache's public and internal contracts.

This closes #13.

Design and API impact

DialCache.flushAll() was unsafe as a library operation because its Redis implementations ignored keyPrefix and could delete unrelated data across every cluster primary. This change removes the capability rather than replacing it:

• remove DialCache.flushAll()
• remove flushAll() from DialCacheRedisClient
• remove local and Redis internal flush forwarding
• remove node-redis cluster-primary administration and GLIDE flushall routing
• update package-consumer types, mocks, tests, and README documentation

This is an intentional API break. The PR does not add namespace clearing, local clearing, a compatibility alias, or any release/versioning workflow change.

Test design

Raw Redis flushAll() remains only in isolated integration-test fixture setup.

The Redis Cluster recovery test now creates a fresh DialCache instance with the same cache-key identity after SCRIPT FLUSH. That forces real remote reads across cluster shards and verifies per-node script recovery without depending on a library flush API.

The packed TypeScript consumer both implements DialCacheRedisClient without a flush method and asserts that neither public contract exposes flushAll.

Validation

Validated on Node v22.22.0:

• corepack pnpm check
  • strict typecheck
  • 5 release-version tests
  • 101 unit tests
  • ESM/CJS builds and declarations
  • packed ESM/CJS/type consumer
• focused Redis Cluster integration test: 3 passed
• corepack pnpm test:integration: 46 passed across Redis 6.2, Valkey, and a three-node Redis Cluster
• git diff --check
• production, README, and generated-declaration scan contains no flush capability