v0.5.20 — hotfix orchestrator mount race

Hotfix on top of v0.5.19. The v0.5.19 "all 19 tiles live" Playwright verification was a lucky run on a warm module cache; on a cold cache (real users on first navigation) the orchestrator boot raced module script execution and snapshotted the registry with only one tile in it. The remaining 18 sat in the registry with mounted: false for the lifetime of the page — visible empty cards despite a live daemon, no API calls firing for tile endpoints (/api/adapters, /api/reliability, /api/actuator-journal, /api/predictor-cockpit, …).

Fixed — correctness

• Orchestrator boot race: 18/19 tiles silently never mounted. _scheduleBoot() queued a microtask after the first register() call. Module scripts execute as separate tasks, so the microtask drained before the other 18 tile modules finished loading; their registrations landed in _registry after _runBoot had already snapshotted it, and _bootScheduled=true blocked any re-run. Replaced the whole boot-snapshot design with per-tile mount-on-register (_mountByPriority called directly from register()). The connection budget still handles burst protection; no global synchronization point survives, so no race. Verified via Playwright on a cold cache: 19/19 tiles mount, every tile endpoint fires.

• StaticFiles served no Cache-Control header. Without it browsers fall back to Last-Modified heuristic freshness (~10% of age) and can pin stale JS for hours after a fix ships — exactly why this bug survived 28h+ unnoticed on the running dashboard. Mounted via a _NoCacheStatic subclass that adds Cache-Control: no-cache on successful static responses; ETag revalidation now fires on every load (~1 ms warm), so future patches are picked up on the next navigation.

• One-shot cache-bust on the orchestrator import URL. Even after the no-cache header ships, the already-cached _orchestrator.js URL stays valid by browser heuristic until eviction. Added ?v=mount-on-register query to every tile's orchestrator import + the modulepreload hint, forcing one fresh fetch under the new cache policy. Future orchestrator edits don't need the query string bumped — they'll be picked up via no-cache revalidation.

Verified end-to-end

Playwright on cold cache after dashboard restart:

• Mounted: 19/19 tiles (was 1/19 — only live-telemetry-tile, the sole priority='critical' entry)
• Network: every tile endpoint fires within first second of load
• Static assets carry Cache-Control: no-cache, ETag revalidates 1ms

Full diff: v0.5.19...v0.5.20