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/goal/invariants.test.js

@@ -0,0 +1,56 @@
+// Invariant predicate library — these are the "milestone done" truths the
+// Settlement Contract relies on. Locking them guards against the closed-loop
+// regressions the v0.4.1 audit surfaced (e.g. M2_bed must be able to close via
+// a recorded bed LOCATION once actions.js writes locations.bed, not only via a
+// transient carried-bed item).
+
+import { test } from "node:test";
+import assert from "node:assert/strict";
+
+import {
+	worldFromSnapshot,
+	bedSecured,
+	foodSecure,
+	stoneTier,
+	locationExists,
+	hasItem,
+} from "./invariants.js";
+
+const w = (snap) => worldFromSnapshot(snap);
+
+test("bedSecured: met by a carried bed item", () => {
+	assert.equal(bedSecured().met(w({ inventory: { red_bed: 1 } })), true);
+});
+
+test("bedSecured: met by a recorded bed LOCATION (M2 monotonicity after the bed is placed)", () => {
+	// The carried item is gone (consumed by placement) but the location was
+	// recorded — M2 must stay satisfied so the contract doesn't loop
+	// gather.wool→craft.bed for a bed that physically exists.
+	assert.equal(bedSecured().met(w({ inventory: {}, locations: { bed: { x: 1, y: 64, z: 1 } } })), true);
+});
+
+test("bedSecured: unmet with neither a bed item nor a bed location", () => {
+	assert.equal(bedSecured().met(w({ inventory: {}, locations: {} })), false);
+});
+
+test("foodSecure: cooked staple, well-fed, or hasFood — but not raw materials", () => {
+	assert.equal(foodSecure().met(w({ inventory: { bread: 1 } })), true);
+	assert.equal(foodSecure().met(w({ inventory: {}, food: 18 })), true);
+	assert.equal(foodSecure().met(w({ inventory: {}, hasFood: true })), true);
+	assert.equal(foodSecure().met(w({ inventory: { cobblestone: 40 }, food: 10 })), false);
+});
+
+test("stoneTier: needs all three stone tools AND a furnace", () => {
+	assert.equal(stoneTier().met(w({ inventory: { stone_axe: 1, stone_pickaxe: 1, stone_sword: 1 } })), false);
+	assert.equal(stoneTier().met(w({ inventory: { stone_axe: 1, stone_pickaxe: 1, stone_sword: 1, furnace: 1 } })), true);
+});
+
+test("locationExists: pure key-presence over locations (no item required)", () => {
+	assert.equal(locationExists("shelter").met(w({ locations: { shelter: { x: 0, y: 64, z: 0 } } })), true);
+	assert.equal(locationExists("shelter").met(w({ locations: {} })), false);
+});
+
+test("hasItem('torch', 4): the M6 lighting threshold", () => {
+	assert.equal(hasItem("torch", 4, "torch").met(w({ inventory: { torch: 3 } })), false);
+	assert.equal(hasItem("torch", 4, "torch").met(w({ inventory: { torch: 4 } })), true);
+});