chore(GWC-31): relabel perf-pass GWC-3x comments to PERF-nn; tracker housekeeping

Sweep code/doc comments citing unregistered GWC-30/GWC-31 (2026-08-15 perf
pass) to PERF-02/PERF-07/PERF-22, keyed to task numbers in
docs/plans/2026-08-15-perf-review-remediation.md; add a PERF-ID register
table to that plan. Genuine cycle-2 GWC-30 citations (gateway-side frame-
reader 4-byte prefix fix in Server/Workers/WorkerFrameReader.cs and its
test) are left untouched.

Add a line to REVIEW-PROCESS.md reserving the GWC/WRK/IPC/SEC/CLI/TST
prefixes for the archreview domain registers.

Tracker housekeeping per archreview/2026-08-19/00-overall.md:
- GWC-16 -> Won't fix (rationale: PERF(followup) comment documents the
  double session lookup as measured-negligible, deliberately not collapsed)
- IPC-08 -> Done (closed by 7c1ea12/a1a38b5; residual tracked as IPC-34)
- IPC-31 -> Done (superseded by GWC-28's write-time sequence stamping)
- TST-06, TST-17 rows refreshed per cycle-3 60-testing-docs-gaps.md
- WRK-31 (and defensively WRK-29/30) registered as reserved/do-not-reuse
  interim IDs burned by e913dab, in both the cycle-2 tracker and the
  cycle-2 worker remediation doc

Flip Batch C to Done in archreview/2026-08-19/remediation/00-tracking.md.

Worker-side files (Worker/Ipc/WorkerFrameReader.cs, WorkerFrameWriter.cs)
are comment-only edits, unverified here (net48 x86, windev-only build).

src/ZB.MOM.WW.MxGateway.Server/Metrics/GatewayMetrics.cs

@@ -43,7 +43,7 @@ public sealed class GatewayMetrics : IDisposable
     private readonly ConcurrentDictionary<long, Func<int>> _eventStreamBacklogSources = new();
     private long _nextEventStreamBacklogSourceId;
 
-    // GWC-30: the same pull model for the worker event queue depth. It replaces a pushed scalar that
+    // PERF-02: the same pull model for the worker event queue depth. It replaces a pushed scalar that
     // every WorkerClient wrote twice per event (staged, consumed) under _syncRoot — a process-wide
     // lock on the hottest path, and last-writer-wins across sessions, so the gauge reported one
     // arbitrary session's backlog instead of the gateway's. Each client registers a source returning
@@ -210,7 +210,7 @@ public sealed class GatewayMetrics : IDisposable
     /// <param name="method">Name of the command method.</param>
     public void CommandStarted(string method)
     {
-        // GWC-30: the three command counters run two-to-three times per gRPC call, so they use
+        // PERF-02: the three command counters run two-to-three times per gRPC call, so they use
         // Interlocked rather than _syncRoot — the same idiom as EventReceived. Nothing here needs a
         // consistent multi-field view; GetSnapshot reads each with Interlocked.Read.
         Interlocked.Increment(ref _commandsStarted);
@@ -281,7 +281,7 @@ public sealed class GatewayMetrics : IDisposable
     ///     Registers a live depth source for the worker event queue-depth gauge and returns a handle
     ///     that removes it when disposed. Each <c>WorkerClient</c> registers once and reports its own
     ///     undelivered (staged + queued) event count, so the gauge is the gateway-wide sum instead of
-    ///     the last value any one session happened to push (GWC-30).
+    ///     the last value any one session happened to push (PERF-02).
     /// </summary>
     /// <param name="depth">
     ///     Returns this worker client's current undelivered event count. Invoked only at collection
@@ -460,7 +460,7 @@ public sealed class GatewayMetrics : IDisposable
     {
         // Compute the live queue depths outside _syncRoot: the sources are the subscriber channels'
         // Count (their own locks) and the worker clients' interlocked counters, neither of which may
-        // run under this lock. GWC-15, GWC-30.
+        // run under this lock. GWC-15, PERF-02.
         int workerEventQueueDepth = GetWorkerEventQueueDepth();
         int grpcEventStreamQueueDepth = GetGrpcEventStreamQueueDepth();
         lock (_syncRoot)
@@ -521,7 +521,7 @@ public sealed class GatewayMetrics : IDisposable
         }
     }
 
-    // Sums the undelivered event backlog across every live worker client (GWC-30).
+    // Sums the undelivered event backlog across every live worker client (PERF-02).
     private int GetWorkerEventQueueDepth() => SumSources(_workerEventQueueDepthSources);
 
     // Sums the live backlog across every registered event-stream subscriber.