mesh-healers act and artifact-store-tools sweeps without the controller's lease

The controller ended by its unassignment, so its lease key is absent for good
and the healers stayed in shadow while nobody swept the artifact store (issue
1126, A4). Drop both gates and each manifest's read of mesh-controller.lease;
the would bucket stays readable until its keys expire.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

modules/artifact-store-tools/module.json

@@ -27,8 +27,7 @@
     "mesh-delivery-builder.builds",
     "mesh-delivery-builder.build-log",
     "mesh-delivery-indexer.manifests",
-    "node-engine.have",
-    "mesh-controller.lease"
+    "node-engine.have"
   ],
   "state": [
     "findings"