5 new test files covering all 13 changed production files:
- estimateSizeFast.test.ts: 16 tests for fast size estimator (circular ref
protection, early exit, nested structures, Map safety)
- eviction-guards-apiKeyRotator.test.ts: 5 tests for Map eviction guards
(!has() check prevents evicting existing keys on update)
- eviction-guards-codexQuotaFetcher.test.ts: 4 tests for connectionRegistry
and quotaCache eviction guards
- rateLimitManager-idle-eviction.test.ts: 6 tests for idle limiter cleanup,
limiterLastUsed tracking, and shutdown behavior
- registry-direct-exports.test.ts: 20 tests verifying all 8 registries export
plain objects (no Proxy traps, no lazy getters, mutable entries)
Extract estimateSizeFast/isSmallEnoughForSemanticCache into standalone
open-sse/utils/estimateSize.ts to make them testable without importing
the entire chatCore.ts dependency tree.
