Fix E2E test gaps and add comprehensive E2E + parity test suites

- Fix pull consumer fetch: send original stream subject in HMSG (not inbox)
  so NATS client distinguishes data messages from control messages
- Fix MaxAge expiry: add background timer in StreamManager for periodic pruning
- Fix JetStream wire format: Go-compatible anonymous objects with string enums,
  proper offset-based pagination for stream/consumer list APIs
- Add 42 E2E black-box tests (core messaging, auth, TLS, accounts, JetStream)
- Add ~1000 parity tests across all subsystems (gaps closure)
- Update gap inventory docs to reflect implementation status

gaps/execution.md

@@ -0,0 +1,90 @@
+# Category Execution Instructions
+
+Use this runbook to execute one category end-to-end using the `executeplan` skill without running the full test suite.
+
+## Inputs
+- `CATEGORY` (example: `protocol`)
+- `gaps/plans.md` row for that category (contains category gap file, design file, and plan file paths)
+
+## Required Skills
+- `executeplan`
+- `using-git-worktrees` (required before implementation)
+- `finishing-a-development-branch` (required after implementation)
+
+## Execution Flow
+1. Resolve the category row from `gaps/plans.md`.
+2. Read the category's design and plan files from the resolved row.
+3. Announce: `I'm using executeplan to implement this plan.`
+4. Create a brand-new git worktree on a new branch and verify clean status.
+5. Execute the plan in batches (`executeplan` default batching), with checkpoints between batches.
+6. Run only targeted unit tests for the category after each batch; do not run full-suite tests.
+7. After implementation, verify the category gap file reflects the completed work.
+8. Update the `Status` column in `gaps/plans.md` for the category:
+   - `complete` if no `MISSING` or `PARTIAL` rows remain
+   - `<N> remaining` where `N = MISSING + PARTIAL`
+
+## Strict Test Scope Policy
+- Never run unscoped full test commands such as:
+  - `dotnet test tests/NATS.Server.Tests/NATS.Server.Tests.csproj`
+- Always use targeted test execution, for example:
+  - `dotnet test tests/NATS.Server.Tests/NATS.Server.Tests.csproj --filter "FullyQualifiedName~Protocol"`
+  - `dotnet test tests/NATS.Server.Tests/NATS.Server.Tests.csproj --filter "FullyQualifiedName~JetStream"`
+  - `dotnet test tests/NATS.Server.Tests/NATS.Server.Tests.csproj --filter "FullyQualifiedName~Auth"`
+- If one filter is too broad, split into multiple narrow filters and run them separately.
+
+## Suggested Category Filter Tokens
+Use these as starting points for `--filter "FullyQualifiedName~<token>"`:
+
+| Category | Token(s) |
+|---|---|
+| `core-server` | `Server`, `Client` |
+| `protocol` | `Protocol`, `Parser` |
+| `subscriptions` | `Subscription` |
+| `auth-and-accounts` | `Auth`, `Account` |
+| `configuration` | `Configuration`, `Config` |
+| `routes` | `Route` |
+| `gateways` | `Gateway` |
+| `leaf-nodes` | `Leaf` |
+| `jetstream` | `JetStream` |
+| `raft` | `Raft` |
+| `mqtt` | `Mqtt` |
+| `websocket` | `WebSocket` |
+| `monitoring` | `Monitoring` |
+| `events` | `Event` |
+| `tls-security` | `Tls`, `Security` |
+| `internal-ds` | `Internal` |
+| `logging` | `Log`, `Logging` |
+| `utilities-and-other` | `IO`, `Server` |
+| `misc-uncategorized` | `Misc`, `Server` |
+
+## Gap Verification Rules (Category Gap File)
+For the category gap file (`gaps/<category>.md`):
+1. Every implemented item must be updated in the Gap Inventory.
+2. Each newly completed row must include:
+   - `Status = PORTED`
+   - concrete `.NET Equivalent` file:line
+   - concise notes for parity behavior
+3. If behavior is still partial, keep `PARTIAL` and document what is still missing.
+4. Do not mark `complete` in `gaps/plans.md` until both `MISSING` and `PARTIAL` counts are zero.
+
+## Status Update Command Snippet
+After finishing a category, compute remaining gaps:
+
+```bash
+remaining=$(awk -F'|' '
+  NF >= 4 {
+    s=$4
+    gsub(/^ +| +$/, "", s)
+    if (s=="MISSING" || s=="PARTIAL") c++
+  }
+  END { print c+0 }
+' "gaps/${CATEGORY}.md")
+
+if [ "$remaining" -eq 0 ]; then
+  status_value="complete"
+else
+  status_value="${remaining} remaining"
+fi
+```
+
+Then write `status_value` into that category row in `gaps/plans.md`.