feat(v0.4.0): vNext — closed-loop world model + settlement contract

Implements the vNext architecture from the research doc: demote the noisy
multi-rail planner in favour of a closed loop (world truth → invariant check)
plus a single utility-driven goal authority.

L1 services (fix no_drop / silent pathfinder hang first):
- InventoryLedger: diff-based "did I actually get it" verifier; acquire-food
  now confirms via ledger.gainedSince instead of the unreliable count/event.
- MotionService.gotoSafe: wall-clock timeout + progress watchdog +
  path_update(noPath/timeout) → structured {reached|stuck|timeout|nopath}.

L3 plan — unify the three competing rails (curriculum/manifesto/storyline):
- Settlement Contract: ordered M0–M9 milestones, each invariant-checked
  against an authoritative world view (early steps delegate to the proven
  curriculum; late game adds farming).
- InvariantChecker + predicate library; GoalManager selects the lowest unmet
  milestone via utility argmax (food-urgency preempts, DEPS-style).
- Wired into the scheduler: bot.js precomputes snapshot.contract; reflex.js
  consumes it in place of the storyline rail. Manifesto L0 still preempts.

Eval + robustness:
- Village Score (single 0..1 metric) on the snapshot + TUI "build" line.
- survive.dig-in skill + dusk_dig_in mode (exposed at night, no bed → cover).
- approach_block helper (GoalNear + lookAt, avoids GoalLookAtBlock #341).

+28 new tests (450 total green). LLM remains entirely off the tick path.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

runtime/goal/village-score.js

@@ -0,0 +1,78 @@
+// Village Score (L5 eval) — one number for "is the bot actually building a
+// settlement, or just walking?" (research §2). The research's formula mixes
+// milestones, food stock, fence closure, lit tiles, uptime, distinct skills
+// and dialog quality. We compute the subset that is *observable* today; fence
+// polygon / lit-tile fraction stay at 0 until those skills exist (the score is
+// honest about what it can measure rather than faking precision).
+//
+// Pure: snapshot + a few derived inputs in, { score, components } out. Score is
+// normalised to 0..1 so a dashboard / TUI can show a single percentage.
+
+const TWO_HOURS_MS = 2 * 60 * 60 * 1000;
+const DISTINCT_SKILL_TARGET = 12;
+
+function clamp01(n) {
+	if (!Number.isFinite(n)) return 0;
+	return n < 0 ? 0 : n > 1 ? 1 : n;
+}
+
+function milestoneFraction(contract) {
+	if (!contract || !contract.total) return 0;
+	return clamp01(contract.completed / contract.total);
+}
+
+function foodSecurity(snapshot) {
+	if (snapshot?.hasFood) return 1;
+	return clamp01((snapshot?.food ?? 0) / 18);
+}
+
+function baseEstablished(snapshot) {
+	const loc = snapshot?.locations ?? {};
+	const want = ["base", "shelter", "chest"];
+	const have = want.filter((k) => loc[k]).length;
+	return clamp01(have / want.length);
+}
+
+function distinctSkillsSucceeded(metrics) {
+	if (!metrics) return 0;
+	const n = Object.values(metrics).filter((m) => (m?.ok ?? 0) > 0).length;
+	return clamp01(n / DISTINCT_SKILL_TARGET);
+}
+
+function uptimeFraction(uptimeMs) {
+	return clamp01((uptimeMs ?? 0) / TWO_HOURS_MS);
+}
+
+function survival(snapshot) {
+	return clamp01((snapshot?.health ?? 0) / 20);
+}
+
+const WEIGHTS = Object.freeze({
+	milestones: 0.35,
+	food: 0.15,
+	base: 0.15,
+	distinctSkills: 0.15,
+	uptime: 0.10,
+	survival: 0.10,
+});
+
+export function computeVillageScore(snapshot, { contract, uptimeMs = 0, metrics = null } = {}) {
+	const components = {
+		milestones: milestoneFraction(contract),
+		food: foodSecurity(snapshot),
+		base: baseEstablished(snapshot),
+		distinctSkills: distinctSkillsSucceeded(metrics),
+		uptime: uptimeFraction(uptimeMs),
+		survival: survival(snapshot),
+	};
+	let score = 0;
+	for (const [k, w] of Object.entries(WEIGHTS)) score += w * components[k];
+	return {
+		score: Math.round(clamp01(score) * 1000) / 1000,
+		components,
+		milestonesCompleted: contract?.completed ?? 0,
+		milestonesTotal: contract?.total ?? 0,
+	};
+}
+
+export const _internal = { clamp01, WEIGHTS, milestoneFraction, foodSecurity, baseEstablished };