docs(mesh-phase4): Tasks 4+6 done (d9071607); Task 3 confirmed hard prereq

Task 4+6 code review re-surfaced the OpcUaPublishActor raw-sink wipe on a
null-factory node (the exact #485/#486 defect Task 3 fixes) — Task 3 must land
before any node flips to FetchAndCache. Ordering already enforces this
(3 → 7 → 10 → 11).

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

docs/plans/2026-07-23-mesh-phase4-cut-driver-configdb.md.tasks.json

@@ -46,10 +46,12 @@
     {
       "id": 4,
       "subject": "Task 4: DriverHostActor \u2014 nullable factory; drop redundant SQL ack-writes",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         1
-      ]
+      ],
+      "commit": "d9071607",
+      "result": "Tasks 4+6 combined (avoid churn). 32+162+6 tests; SPEC-COMPLIANT + APPROVED. Review re-confirmed Task 3 is a HARD PREREQ before any FetchAndCache flip (address-space wipe)"
     },
     {
       "id": 5,
@@ -61,11 +63,13 @@
     {
       "id": 6,
       "subject": "Task 6: Wire LocalDb condition store into DriverHostActor for driver-role",
-      "status": "pending",
+      "status": "completed",
       "blockedBy": [
         4,
         5
-      ]
+      ],
+      "commit": "d9071607",
+      "result": "Tasks 4+6 combined (avoid churn). 32+162+6 tests; SPEC-COMPLIANT + APPROVED. Review re-confirmed Task 3 is a HARD PREREQ before any FetchAndCache flip (address-space wipe)"
     },
     {
       "id": 7,