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/skills/flee.js

@@ -39,7 +39,7 @@ export const skill = Object.freeze({
 	async execute(ctx, args = {}) {
 		const hit = nearestHostile(ctx.bot, args);
 		if (!hit) return { ok: false, code: "no_hostile", detail: "no matching hostile after precondition", worldDelta: null };
-		const res = await fleeFrom(ctx.bot, hit.entity, args.distance ?? 16);
+		const res = await fleeFrom(ctx.bot, hit.entity, args.distance ?? 16, { motion: ctx.motion, blindMs: args.blindMs });
 		if (res.ok) {
 			return {
 				ok: true,
@@ -48,8 +48,10 @@ export const skill = Object.freeze({
 				worldDelta: { fledTo: res.detail?.to ?? null },
 			};
 		}
+		// Prefer the structured code from MotionService (stuck/timeout/nopath);
+		// fall back to string-sniffing the legacy path's message.
 		const msg = String(res.detail ?? "");
-		const code = msg.includes("timed out") ? "timeout" : "failed";
+		const code = res.code ?? (msg.includes("timed out") ? "timeout" : "failed");
 		return { ok: false, code, detail: res.detail, worldDelta: null };
 	},
 	recover(ctx, result) {