feat(v0.4.0): finish vNext plan — anti-loop, skill-graph, worldDelta diff, flee→motion

Completes the remaining v0.4.0 plan items and one fix motivated by a live
in-game observation (flee hanging 30s against a persistent zombie).

- flee → MotionService.gotoSafe: structured {stuck|timeout|nopath} in ~4s with
  a blind-retreat fallback, instead of the observed 30s pathfinder hang + 3
  watchdog replans. Movements setup guarded so it is unit-testable.
- QW5 anti-loop (runtime/anti-loop.js): same skill failing >=3x in 5min →
  30min blacklist (reflex shouldSkip) + one-shot improvement_request
  (bot.js drainFired -> writeProposal).
- 4.1 closed-loop worldDelta: runSkill snapshots inventory before execute and
  attaches the real delta (_invObserved) to every successful result; opt-in
  skill.expectGain asserts the claimed gain or returns world_unchanged.
- 3.6 skill-graph (Plan4MC): declarative requires/produces for ~20 skills;
  prerequisitesMet/canRun/runnableFrontier; GoalManager annotates suggestions
  with blockedBy when prereqs are unmet.

+22 tests (472 total green). Live smoke confirmed dig-in works and no new
errors; flee loop is what this commit's flee migration addresses.

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

runtime/goal/goal-manager.js

@@ -17,6 +17,7 @@
 
 import { SETTLEMENT_CONTRACT } from "./contract.js";
 import { checkInvariants, worldFromSnapshot } from "./invariants.js";
+import { prerequisitesMet } from "./skill-graph.js";
 
 export function createGoalManager({ contract = SETTLEMENT_CONTRACT } = {}) {
 	// Evaluate every milestone; returns the per-milestone invariant status plus
@@ -57,6 +58,14 @@ export function createGoalManager({ contract = SETTLEMENT_CONTRACT } = {}) {
 			suggestedSkill = null;
 		}
 
+		// Annotate the suggestion with skill-graph prerequisite status (Plan4MC).
+		// Observability + a guard surface: if prereqs are unmet the curriculum
+		// chain should already be steering toward them, but we expose the gap.
+		if (suggestedSkill?.skillId) {
+			const pre = prerequisitesMet(suggestedSkill.skillId, world);
+			if (!pre.ok) suggestedSkill = { ...suggestedSkill, blockedBy: pre.missing };
+		}
+
 		const reason = current.urgency > 0 && current.index > unmet[0].index
 			? `urgent:${current.id}(${current.urgency}) preempts ${unmet[0].id}`
 			: `lowest unmet: ${current.id}`;