mesh-watcher stops consuming the controller's doctor-heartbeat (ADR 0564 clause 9)

The watcher hears the self-check's `checked` alone: the consume of mesh-controller.doctor-heartbeat, the subscription
to the controller's seat, the follow switch (takeover.go) and its read of mesh-conditions.takeover are gone. The
manifest test now lists the one consume and the heartbeat-key test refuses the controller's event. No test added.

(issue 774, 774/S11)

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

modules/mesh-watcher/module.json

@@ -3,11 +3,9 @@
   "version": "1",
   "slug": "watch",
   "consumes": [
-    "mesh-controller.doctor-heartbeat",
     "mesh-self-check.checked"
   ],
   "reads": [
-    "mesh-conditions.takeover",
     "mesh-delivery-assigner.seat-holders"
   ],
   "invokes": [