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>

tests/js/venue_crowd.test.js

@@ -128,3 +128,22 @@ test('venue-scene-3d activates/deactivates the crowd layer', () => {
     assert.match(src, /syncCrowd\(false\)/);
     assert.match(src, /v3VenueCrowd/);
 });
+
+test('machine.force commits instantly and dwell holds the forced state', () => {
+    const m = crowd.createCrowdMachine();
+    m.force('ecstatic', 100000);
+    assert.equal(m.current, 'ecstatic');
+    // The real perf state cannot reassert until the dwell window passes.
+    m.update('smoke', 100000 + crowd.STABLE_MS);
+    assert.equal(m.update('smoke', 100000 + crowd.DWELL_MS - 1), null);
+    assert.equal(m.current, 'ecstatic');
+    assert.equal(m.update('smoke', 100000 + crowd.DWELL_MS), 'bored');
+    // Bogus states are ignored.
+    m.force('confused', 200000);
+    assert.equal(m.current, 'bored');
+});
+
+test('celebrate() is exported and no-ops without a manifest/active venue', () => {
+    assert.equal(typeof crowd.celebrate, 'function');
+    assert.equal(crowd.celebrate(), false);
+});