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-01.md

@@ -0,0 +1,48 @@
+# Session 01: Foundation Types
+
+## Summary
+
+Constants, error types, error catalog, protocol definitions, ring buffer, rate counter, stream distribution model, and NKey utilities. These are the leaf types with no internal dependencies — everything else builds on them.
+
+## Scope
+
+| Go File | Features | Feature IDs | Go LOC |
+|---------|----------|-------------|--------|
+| server/const.go | 2 | 582–583 | 18 |
+| server/errors.go | 15 | 833–847 | 92 |
+| server/errors_gen.go | 6 | 848–853 | 158 |
+| server/proto.go | 6 | 2593–2598 | 237 |
+| server/ring.go | 6 | 2889–2894 | 34 |
+| server/rate_counter.go | 3 | 2797–2799 | 34 |
+| server/sdm.go | 5 | 2966–2970 | 39 |
+| server/nkey.go | 3 | 2440–2442 | 14 |
+| **Total** | **46** | | **626** |
+
+## .NET Classes
+
+- `Constants` — server constants and version info
+- `ServerErrorCatalog` — generated error codes and messages
+- `Protocol` — NATS protocol string constants
+- `RingBuffer` — fixed-size circular buffer
+- `RateCounter` — sliding window rate measurement
+- `StreamDistributionModel` — stream distribution enum/types
+- `NkeyUser` — NKey authentication types
+
+## Test Files
+
+| Test File | Tests | Test IDs |
+|-----------|-------|----------|
+| server/errors_test.go | 2 | 297–298 |
+| server/ring_test.go | 2 | 2794–2795 |
+| server/rate_counter_test.go | 1 | 2720 |
+| server/nkey_test.go | 9 | 2362–2370 |
+| server/trust_test.go | 3 | 3058–3060 |
+| **Total** | **17** | |
+
+## Dependencies
+
+- None (leaf session)
+
+## .NET Target Location
+
+- `dotnet/src/ZB.MOM.NatsNet.Server/` — types and enums at root or `Internal/`