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-19.md

@@ -0,0 +1,67 @@
+# Session 19: JetStream Core
+
+## Summary
+
+JetStream engine core — initialization, API handlers, error definitions, event types, versioning, and batching. The central JetStream coordination layer.
+
+## Scope
+
+| Go File | Features | Feature IDs | Go LOC |
+|---------|----------|-------------|--------|
+| server/jetstream.go | 84 | 1368–1451 | 2,481 |
+| server/jetstream_api.go | 56 | 1452–1507 | 4,269 |
+| server/jetstream_errors.go | 5 | 1751–1755 | 62 |
+| server/jetstream_errors_generated.go | 203 | 1756–1958 | 1,924 |
+| server/jetstream_events.go | 1 | 1959 | 25 |
+| server/jetstream_versioning.go | 13 | 1960–1972 | 175 |
+| server/jetstream_batching.go | 12 | 1508–1519 | 568 |
+| **Total** | **374** | | **9,504** |
+
+## .NET Classes
+
+- `JetStreamEngine` — JetStream lifecycle, enable/disable, account tracking
+- `JetStreamApi` — REST-like API handlers for stream/consumer CRUD
+- `JetStreamErrors` — error code registry (208 entries)
+- `JetStreamEvents` — advisory event types
+- `JetStreamVersioning` — feature version compatibility
+- `JetStreamBatching` — batch message processing
+- `JsAccount` — per-account JetStream state
+- `JsOutQ` — JetStream output queue
+
+## Test Files
+
+| Test File | Tests | Test IDs |
+|-----------|-------|----------|
+| server/jetstream_test.go | 320 | 1466–1785 |
+| server/jetstream_errors_test.go | 4 | 1381–1384 |
+| server/jetstream_versioning_test.go | 18 | 1791–1808 |
+| server/jetstream_batching_test.go | 29 | 716–744 |
+| server/jetstream_jwt_test.go | 18 | 1385–1402 |
+| server/jetstream_tpm_test.go | 5 | 1786–1790 |
+| server/jetstream_benchmark_test.go | 12 | 745–756 |
+| **Total** | **406** | |
+
+## Dependencies
+
+- Session 01 (Foundation Types)
+- Session 03 (Configuration)
+- Session 08 (Client Connection)
+- Session 09 (Server Core Part 1)
+- Session 11 (Accounts)
+- Session 17 (Store Interfaces)
+
+## .NET Target Location
+
+- `dotnet/src/ZB.MOM.NatsNet.Server/JetStream/`
+
+## Notes
+
+- **This is a multi-sitting session** — 9.5K Go LOC and 406 tests
+- JetStream errors generated file is 203 features but mostly boilerplate error codes
+- jetstream_test.go has 320 tests — the largest test file
+- Suggested sub-batching:
+  - **19a**: Error definitions and events (209 features, 2K LOC) — mostly mechanical
+  - **19b**: JetStream engine core (84 features, 2.5K LOC)
+  - **19c**: JetStream API (56 features, 4.3K LOC)
+  - **19d**: Versioning + batching (25 features, 743 LOC)
+  - **19e**: Tests (406 tests, batched by test file)