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-12.md

@@ -0,0 +1,53 @@
+# Session 12: Events, Monitoring & Message Tracing
+
+## Summary
+
+Server-side event system (system events, advisory messages), HTTP monitoring endpoints (varz, connz, routez, etc.), and message tracing infrastructure.
+
+## Scope
+
+| Go File | Features | Feature IDs | Go LOC |
+|---------|----------|-------------|--------|
+| server/events.go | 97 | 854–950 | 2,445 |
+| server/monitor.go | 70 | 2166–2235 | 3,257 |
+| server/monitor_sort_opts.go | 16 | 2236–2251 | 48 |
+| server/msgtrace.go | 35 | 2405–2439 | 569 |
+| **Total** | **218** | | **6,319** |
+
+## .NET Classes
+
+- `EventsHandler` — system event publishing
+- `MonitoringHandler` — HTTP monitoring endpoints
+- `ConnInfo`, `ClosedState` — connection monitoring types
+- `HealthZErrorType` — health check error types
+- `MsgTrace`, `MsgTraceEvent`, `MsgTraceEvents` — message tracing
+- `MessageTracer` — tracing engine
+- Various sort option types (16 types)
+
+## Test Files
+
+| Test File | Tests | Test IDs |
+|-----------|-------|----------|
+| server/events_test.go | 52 | 299–350 |
+| server/monitor_test.go | 103 | 2064–2166 |
+| server/msgtrace_test.go | 33 | 2329–2361 |
+| **Total** | **188** | |
+
+## Dependencies
+
+- Session 01 (Foundation Types)
+- Session 08 (Client Connection)
+- Session 09 (Server Core Part 1)
+- Session 11 (Accounts)
+
+## .NET Target Location
+
+- `dotnet/src/ZB.MOM.NatsNet.Server/Monitoring/`
+- `dotnet/src/ZB.MOM.NatsNet.Server/Events/`
+
+## Notes
+
+- Monitor endpoints map to ASP.NET Core minimal API or controller endpoints
+- Events system uses internal pub/sub — publishes to `$SYS.*` subjects
+- This is a larger session (~6.3K LOC) but the code is relatively straightforward
+- Monitor has 103 tests — allocate time accordingly