wave 1 (platform stream): background-observability accuracy + owner-driven follow-ups

- observability: liveness-gated stale-job recovery, extraction run registry on globalThis with
  explicit 'embedding' phase, /api/jobs force-dynamic, client refresh nudges at every seam
- headless: providerSafePng canonicalizer (multi-IDAT Chrome PNGs → single-IDAT) fixing qwen 400s
- composer: Enter routes through pure enterAction — accepts a pending plan verdict (owner decision)
- markdown chrome: session-scoped mermaid overlay + md-blocks component set + pan-zoom math,
  corner-copy (clipboard grant in electron main), math/table/code block fixes, heading weight 900

543/543 tests; typecheck/lint/build clean

app/api/jobs/route.ts

@@ -1,5 +1,7 @@
 import { isTurnRunning, listJobs } from "@/src/server";
 
+export const dynamic = "force-dynamic";
+
 /**
  * Job status polling endpoint (contracts.ts "THE ASYNC PROTOCOL" §4): the
  * client's ONE central poller fetches this while any job runs (and slowly