feat(v0.4.1): make the Settlement Contract honest end-to-end

Patches each link of the closed-loop chain (world-truth -> invariant ->
dispatch -> worldDelta -> milestone) so the contract can no longer advance
on a lie or stall on an unreachable milestone, and surfaces the result on
the monitor.

- Unblock M6_lighting: add gather.coal producer (mirrors gather.stone,
  strict expectGain), register it, add the skill-graph node, and make
  curriculum.shelter.torch two-step (gather coal -> craft torch). craft.torch
  needed coal but no skill produced it, so the contract pinned on M6 forever
  and starved M7/M8/M9. One curriculum edit fixes both rails.
- M8 no longer falsely satisfied: build-shelter records locations.shelter
  only on real progress (setLocation moved below the no_progress guard).
- M2_bed made monotonic: sleepInBed writes locations.bed when the bot places
  its own bed, so M2 stays met after the carried bed item is consumed.
- Observability: new ink-free tui/format.js helper renders per-tick
  state / firing rail / active skill / blocked prerequisite / stall reason
  in the monitor header (fields bot.js already computes but never showed).
- Harden the valid-skill-id guardrail: skillRegistryPrompt preserves the
  "NEVER invent" footer when truncating (a growing registry was dropping it),
  and fix the stale "tech-tree > autonomous" reflex chain in the escalation
  prompt.

Tests: 494/494 passing; new build-shelter / invariants / format suites plus
skill-graph, curriculum, skill-registry cases. lint-patch clean. Deferred
audit findings recorded in plans/v0.4.0-vnext.md (local).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

runtime/skills/index.js

@@ -35,6 +35,7 @@ import { skill as escapePitSafe } from "./escape-pit-safe.js";
 import { skill as diagPhysics } from "./diagnose-physics.js";
 import { skill as diagScan, matchSkill as diagMatch } from "./diagnose-scan.js";
 import { skill as gatherStone } from "./gather-stone.js";
+import { skill as gatherCoal } from "./gather-coal.js";
 import { skill as gatherWool } from "./gather-wool.js";
 import { skill as acquireFood } from "./acquire-food.js";
 import { skill as scoutFood } from "./scout-food.js";
@@ -84,6 +85,7 @@ register(diagPhysics);
 register(diagScan);
 register(diagMatch);
 register(gatherStone);
+register(gatherCoal);
 register(gatherWool);
 register(acquireFood);
 register(scoutFood);