fix(IPC-23,IPC-24,IPC-25,IPC-32): proto-comment regen wave + codegen-freshness guards

Proto comments (comment-only, no wire change):
- mxaccess_worker.proto GatewayHello.max_frame_bytes: every worker->gateway frame
  must serialize within the negotiated max; reply builders truncate (IPC-23).
- mxaccess_gateway.proto DrainEventsReply: count-cap + byte-cap, drain-until-empty
  caller contract (IPC-23).
- mxaccess_gateway.proto ReplayGap.oldest_available_sequence: empty-ring value is
  highest-observed+1, oldest-1 resume formula stays valid (GWC-25 deferred amendment).

Regen wave: Contracts/Generated (C# XML doc), rust vendored protos (byte-copy),
Go bindings (worker binding was genuinely stale - lacked MaxFrameBytes entirely),
Python worker _pb2 (real descriptor delta), Java aggregates (javadoc, zero
protobuf-version churn under the pinned toolchain), client descriptor set.

IPC-24: pinned Java toolchain regenerates with no gencode-version churn, so the
unconditional churn-revert step in ci.yml is a fossil - deleted it; git diff is
now a true message-level drift gate for the single-file Java aggregates.

IPC-25: pin protoc-gen-go v1.36.11 / protoc-gen-go-grpc 1.6.2 in the Go generate
script (+ fix a latent pwsh-7 parse bug); add Check 4 to check-codegen.ps1
(regenerate Go+Python bindings, fail on diff, tool-missing fails not skips); add
the pinned-generator installs to the portable CI job.

IPC-32: relabel check-codegen banners 1/4..4/4 (folded into the Check 4 edit).

Docs: ClientProtoGeneration.md, Contracts.md, GatewayTesting.md, build.gradle
checkGeneratedClean caveat. Tracking: IPC-23/24/25/32 -> Done, GWC-25 proto note
resolved, change-log 2026-08-07.

src/ZB.MOM.WW.MxGateway.Contracts/Generated/MxaccessGateway.cs

@@ -22796,6 +22796,12 @@ namespace ZB.MOM.WW.MxGateway.Contracts.Proto {
     private static readonly pb::FieldCodec<global::ZB.MOM.WW.MxGateway.Contracts.Proto.MxEvent> _repeated_events_codec
         = pb::FieldCodec.ForMessage(10, global::ZB.MOM.WW.MxGateway.Contracts.Proto.MxEvent.Parser);
     private readonly pbc::RepeatedField<global::ZB.MOM.WW.MxGateway.Contracts.Proto.MxEvent> events_ = new pbc::RepeatedField<global::ZB.MOM.WW.MxGateway.Contracts.Proto.MxEvent>();
+    /// <summary>
+    /// The reply is bounded by both a server-side count cap and the negotiated
+    /// worker-frame byte cap; a reply may therefore carry fewer events than
+    /// `max_events` and fewer than are queued. Callers drain iteratively until an
+    /// empty reply.
+    /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]
     public pbc::RepeatedField<global::ZB.MOM.WW.MxGateway.Contracts.Proto.MxEvent> Events {
@@ -24510,6 +24516,11 @@ namespace ZB.MOM.WW.MxGateway.Contracts.Proto {
     /// after_worker_sequence = oldest_available_sequence - 1 in the next
     /// StreamEventsRequest, which will cause the server to replay starting at
     /// oldest_available_sequence (the first retained event).
+    /// When nothing is retained (the replay ring is empty), this is the next sequence
+    /// that can be delivered — `highest observed + 1` — and the `oldest - 1` resume
+    /// formula remains valid: it resolves to the highest sequence already seen, so the
+    /// follow-up resume replays nothing, reports no gap, and every newer live event
+    /// passes. The interval evicted is unchanged.
     /// </summary>
     [global::System.Diagnostics.DebuggerNonUserCodeAttribute]
     [global::System.CodeDom.Compiler.GeneratedCode("protoc", null)]