Implements RouteResultCache with fixed-capacity LRU eviction and atomic generation-based invalidation (Go ref: client.go routeCache, maxResultCacheSize=8192). Fixes AccountGoParityTests namespace ambiguity introduced by new test file.
Add ProxyProtocol.cs implementing PROXY v1/v2 header parsing (Go ref: server/proxy_proto.go). Port 29 PROXY protocol tests and 120 SubList Go-parity tests covering ReverseMatch, HasInterest, NumInterest, SubjectsCollide, cache hit rate, empty tokens, and overlapping subs. Go refs: TestProtoParseProxyV1, TestSublistReverseMatch, TestSublistHasInterest, TestSublistNumInterest, and 25+ more.
