feat(career): badge ceremony — the crowd erupts, the stamp drops (#941)

Earning a genre badge now stages the full moment (career v2, WS1):

- venue-crowd.js gains a public celebrate(): machine.force('ecstatic')
  commits instantly (bypassing STABLE_MS/DWELL_MS; the stamped
  lastSwitchAt makes the dwell window HOLD the forced state before the
  real perf machine reasserts) + a cheer stinger via the same
  _lastStingerAt=-Infinity bypass the end-of-song reaction uses. If a
  stinger/intro owns the idle layer, the ecstatic loop is queued via
  _pendingLoop exactly like onPerformanceState. No-op without a
  manifest/active venue.
- career detectNewBadges() calls badgeCeremony(): crowd first, then a
  body-appended full-screen overlay 300ms later (it cannot live in
  #pp-overlay — #plugin-career is display:none during playback): dimmed
  backdrop, the bronze stamp slamming in with a shine sweep, a 42-piece
  canvas confetti burst, click-or-4s dismiss.
- prefers-reduced-motion: chime + fbNotify only, no overlay.

Tests: machine.force commit/dwell-hold/bogus-state, celebrate export +
no-manifest no-op, celebrate-called-once-per-badge, crowd-absent and
crowd-throwing degradation.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

CHANGELOG.md

@@ -8,6 +8,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- **Badge ceremony in the venue** — earning a genre badge now stages a moment:
+  the crowd layer erupts (new public `v3VenueCrowd.celebrate()` — instant
+  ecstatic loop bypassing the stability/dwell hysteresis, plus a cheer stinger;
+  a no-op without a venue pack) and a full-screen overlay drops the bronze
+  stamp with a shine sweep and a confetti burst over whatever screen is active
+  (badges land right after `stats:recorded`, while the player is still up).
+  Click or wait ~4s to dismiss; `prefers-reduced-motion` gets the existing
+  chime + notification only. The stamp still slams into the passport book on
+  next open, unchanged.
 - **Career passports (backend)** — the badge-journey layer on top of career stars.
   New career-plugin endpoints: `GET /api/plugins/career/passports` (per-instrument
   passport walls: genre badges computed on read from `song_stats` × the library's