feat(FN-3450): add mesh task create replication across nodes

Implements distributed mesh task creation by adding replicated create primitives to the core store, wiring new API routes (`register-mesh-routes.ts`) that replicate task creation across clustered nodes while preserving remote-targeting metadata, and updating the dashboard's task creation flow accord

Fusion-Task-Id: FN-3450

docs/task-management.md

@@ -382,6 +382,15 @@ At dispatch time, scheduler routing is persisted on the task as:
 - `effectiveNodeId`
 - `effectiveNodeSource` (`task-override`, `project-default`, or `local`)
 
+### Create-time routing semantics
+
+Cluster-aware task creation separates two routing decisions:
+
+- **Transport node**: which node receives the `POST /api/tasks` request (can be local or proxied remote).
+- **Execution target** (`Task.nodeId`): which node should run the task later.
+
+These are intentionally independent. Routing a create request through node A does not force execution on node A unless `Task.nodeId` also points there.
+
 ### Per-task node override
 
 You can set or clear a task override from: