docs(mesh): Phase 2 live-gate record + correct the buffer-size rationale

Flipped the docker-dev rig end-to-end to MeshTransport:Mode=ClusterClient
(OTOPCUA_MESH_MODE, no rebuild) and ran the gate. PASSED for the transport:
deploy seals on ClusterClient, a stopped node fails the deploy naming it, the
MaintenanceMode hatch shrinks the DB-sourced contact set live (6->5->6 on both
centrals independently), and the frame-size canary stayed silent.

Four findings, recorded in 2026-07-22-mesh-phase2-live-gate.md:

  A. A 10-30s post-restart delivery window exists, but the DPS control fails
     identically -- it is a cluster-convergence property, not a Phase 2
     regression. Running the control is the only reason this is a note and not
     a false attribution.

  B. buffer-size=0's stated rationale was OVERSTATED. A node applies a TimedOut
     deployment anyway -- live-observed at +44s -- via DriverHostActor.Bootstrap
     replaying the orphan Applying row on restart. Zero buffering removes the
     silent, timer-driven replay, not the boot-time DB one. Corrected in the
     plan decisions table, Configuration.md, and CLAUDE.md; the decision stands,
     the justification narrowed.

  C. Stopping BOTH centrals strands the non-seed nodes at the Akka membership
     layer (frozen mid-Exiting, not Unreachable, so auto-down does not help).
     Transport-independent; a Phase 7 downing/rejoin drill item.

  D. The AdminUI driver Restart/Reconnect buttons (DriverStatusPanel) are
     rendered by no page -- orphaned since v3 Batch 2 retired /clusters/{id}/
     drivers. So gate steps 6/7 could not run; the driver-control node-side leg
     is proven live only because DispatchDeployment shares its EventStream path.

Step 8's planned log-signal does not exist (HandleApplyAck is silent on
success); proven instead by both centrals independently logging per-instance
ClusterClient creation, which a singleton cannot.

Also adds a repo-root .dockerignore: docker-dev/Dockerfile does COPY . ., which
was pulling .claude/worktrees (19GB of agent checkouts with their own bin/obj)
into the build context and exhausting the Docker VM disk mid-COPY.

Rig restored to Mode=Dps, six members, no leftover maintenance flags.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW

docs/plans/2026-07-22-mesh-phase2-clusterclient-transport.md.tasks.json

@@ -128,7 +128,8 @@
     {
       "id": 10,
       "subject": "Task 10: live gate on docker-dev (11 steps; step 4 = deploy-seal semantics, step 8 = per-node/contact-rotation discriminator [replaces the dropped Task 6 assertion \u2014 do not skip], step 9 = both-centrals drop behavior)",
-      "status": "pending",
+      "status": "completed",
+      "note": "PASSED for the transport (steps 1-5, 8, 11 green; flip end-to-end via OTOPCUA_MESH_MODE=ClusterClient). Record: 2026-07-22-mesh-phase2-live-gate.md. Steps 6/7 NOT RUN (no UI surface for driver-control \u2014 finding D, DriverStatusPanel is orphaned; no alarms configured). Step 8's stated log-signal does not exist (HandleApplyAck is silent on success \u2014 finding E); proven instead by both centrals independently logging per-instance ClusterClient creation + rebuild, which a singleton cannot. FOUR findings: A) 10-30s post-restart delivery window is PRE-EXISTING (DPS control failed identically); B) buffer-size=0 rationale OVERSTATED \u2014 a node applies a TimedOut deploy anyway via Bootstrap() orphan-row replay at +44s, corrected in 3 docs; C) stopping BOTH centrals strands non-seed nodes at the membership layer (Phase 7 drill, transport-independent); D) driver Restart/Reconnect UI orphaned since v3 Batch 2. Rig restored to Dps default.",
       "classification": "high-risk",
       "blockedBy": [
         8,