Ask the root-free word of the controller's verb, which answers, and say every failed ask, so Telegram carries asks that offer an approval again (issue 774)

The messenger asked seat:node-engine.root-free@<machine>, which nothing on the mesh answers (the engine's acts are
left out of its declared state, mesh-host #178; ADR 0571 §11's self-check probe is not held either), and deleted
its kept word on each failure without a log line: every ask from an agent or a merge was held, silently.

Quick fix: point RootFreeVerb back at mesh-controller.root-free. Thorough fix: the same, plus every failed ask is
logged with its error, the failure is kept beside the word and becomes the held ask's reason, a fresh word is no
longer thrown away by one failed ask (an answer is still judged only on a word asked then), and a held ask whose
reason changes is logged. Chose thorough: the silence is what hid the fault for a day.

modules/messenger/module.json

@@ -94,7 +94,7 @@
   "invokes": [
     "seat:mesh-controller.conditions",
     "seat:mesh-conditions.conditions",
-    "seat:node-engine.root-free",
+    "seat:mesh-controller.root-free",
     "seat:issue-tracker.tracking"
   ],
   "reads": [