feat(factory): expose address cache hit/miss metrics (closes #611)

[Ranjeet2063]

Summary

Exposes counters tracking cache hits, misses, and current size for the factory address resolution cache (FactoryModule and StreamsModule), enabling consumers and operators to monitor cache performance and tune concurrency and cache sizing (closes #611).

Key Changes

• src/factory.ts:
  • Defined and exported CacheMetrics interface ({ hits: number; misses: number; size: number }).
  • Added private counters _addressCacheHits and _addressCacheMisses in FactoryModule.
  • Updated streamAddress to record hits (both positive and unexpired negative hits) and misses.
  • Added getAddressCacheMetrics(): CacheMetrics and resetAddressCacheMetrics(): void.
• src/streams.ts:
  • Added convenience methods getAddressCacheMetrics() and resetAddressCacheMetrics() on StreamsModule delegating to _factory.
• src/index.ts:
  • Re-exported FactoryModule and type CacheMetrics.
• src/tests/factory.test.ts:
  • Added 5 comprehensive test cases verifying initial state, positive/negative hit and miss tracking, metric reset, and cache clearing.

Verification

• vitest run src/tests/factory.test.ts: 24/24 tests passing.
• Full build (rm -rf dist && tsc -p tsconfig.build.json && rollup -c rollup.config.mjs) passed cleanly.
• Full vitest suite: 81/81 test files passing (1026 passing tests).

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