cooling.gate-off: a gate setting trips in range and is off at its far end

The acceptance catalog gains the test behind forgectrl 9e44fdc: the
coolant ceiling set just over its legal minimum must trip OVERTEMP with
a hold and fire blocked at the next run start; set to its top the engine
must skip the gate (verdict OK), report it in gates_off on /status and
/cool/status, and log the run-start line; the original values are
restored, on failure too, and proven restored. Five host cases against a
scripted engine. The cooling covers map now names the files that carry
gate state (gates, settings, status, the panel) and corrects a glob that
matched nothing: the GRBL cooling client is src/glowforge_cooling.c, not
src/gfcool*. The fake forgectrl serves /logs/tail and keeps blank form
values as "clear", which is what the daemon does with them.

Docs: COOLING.md section 8 carries each setting's legal range and
recommended band and a new 8a on turning a gate off; SAFETY.md names
what no setting can reach; ACCEPTANCE.md records that gates are
exercised through the settings API, never GFCOOL_* env overrides;
BRINGUP item 19 records the pattern as landed and the catalog is 43.

forgectrl pin moves to 9e44fdc; fetch-verified.

docs/SAFETY.md

@@ -205,7 +205,11 @@ would not allow.
   finish the queue tail so a controlled stop can never leave FIRE driven.
 - **Coolant fire gates.** The armed window requires a fresh `fire_ok` verdict
   from the cooling engine (flow verification, over-temperature, lid-IR
-  emission witness); a stale or failed verdict relocks in-process.
+  emission witness); a stale or failed verdict relocks in-process. The
+  thermal gates are settings with a wide range whose far end turns the gate
+  off by value (`COOLING.md` §8a), loudly; the fresh-report rule, the
+  emission witness, the dead-man and the latch are not settings and stay in
+  force whatever the gates are set to.
 - **Safety door.** `doors` (lid) and `interlock` (loop open) are the core's
   safety-door signal, shown to the core only while it is in a job-time state
   (cycle, hold, tool change, door): a running job parks with a planned