feat: port session 07 — Protocol Parser, Auth extras (TPM/certidp/certstore), Internal utilities & data structures

Session 07 scope (5 features, 17 tests, ~1165 Go LOC):
- Protocol/ParserTypes.cs: ParserState enum (79 states), PublishArgument, ParseContext
- Protocol/IProtocolHandler.cs: handler interface decoupling parser from client
- Protocol/ProtocolParser.cs: Parse(), ProtoSnippet(), OverMaxControlLineLimit(),
  ProcessPub/HeaderPub/RoutedMsgArgs/RoutedHeaderMsgArgs, ClonePubArg(), GetHeader()
- tests/Protocol/ProtocolParserTests.cs: 17 tests via TestProtocolHandler stub

Auth extras from session 06 (committed separately):
- Auth/TpmKeyProvider.cs, Auth/CertificateIdentityProvider/, Auth/CertificateStore/

Internal utilities & data structures (session 06 overflow):
- Internal/AccessTimeService.cs, ElasticPointer.cs, SystemMemory.cs, ProcessStatsProvider.cs
- Internal/DataStructures/GenericSublist.cs, HashWheel.cs
- Internal/DataStructures/SubjectTree.cs, SubjectTreeNode.cs, SubjectTreeParts.cs

All 461 tests pass (460 unit + 1 integration). DB updated for features 2588-2592 and tests 2598-2614.

docs/plans/phases/phase6sessions/session-07.md

@@ -0,0 +1,39 @@
+# Session 07: Protocol Parser
+
+## Summary
+
+The NATS protocol parser — parses raw bytes from client connections into protocol operations (PUB, SUB, UNSUB, CONNECT, etc.). Extremely performance-critical.
+
+## Scope
+
+| Go File | Features | Feature IDs | Go LOC |
+|---------|----------|-------------|--------|
+| server/parser.go | 5 | 2588–2592 | 1,165 |
+| **Total** | **5** | | **1,165** |
+
+## .NET Classes
+
+- `ProtocolParser` — state-machine parser for NATS wire protocol
+- `ClientConnection` (partial — parser-related methods only)
+
+## Test Files
+
+| Test File | Tests | Test IDs |
+|-----------|-------|----------|
+| server/parser_test.go | 17 | 2598–2614 |
+| **Total** | **17** | |
+
+## Dependencies
+
+- Session 01 (Foundation Types — protocol constants, errors)
+
+## .NET Target Location
+
+- `dotnet/src/ZB.MOM.NatsNet.Server/Protocol/`
+
+## Notes
+
+- Only 5 features but 1,165 LOC — these are large state-machine functions
+- Must use `ReadOnlySpan<byte>` and avoid allocations in the parse loop
+- The parser is called for every byte received — benchmark after porting
+- Consider using `System.IO.Pipelines` for buffer management