feat(turn): D&D 5e death saves — success/fail tracking

Old model broken: single deathSaves counter, 3=revive. No fails tracked,
successes conflated with fails. DM couldn't model real death save outcomes.

New model (D&D 5e):
- deathSave(enc, id, type, n) — type='success'|'fail', n=1|2|3
- Participant fields: deathSaves (successes), deathFails, isStable, isDying
- 3 successes = stable (0hp unconscious, safe until healed)
- 3 failures = dead (isDying, caller animates removal)
- Toggling same pip = undo that pip
- Returns { patch, log, status } — status: 'stable'|'dead'|'pending'
  isDying back-compat flag kept for App.js removal animation

App.js:
- UI split into green ✓ saves row + red ✕ fails row
- Status badges: Stabilized (emerald) / Dying (red pulse)
- handleDeathSaveChange(participantId, type, saveNumber) — new sig
- makeParticipant init: deathFails + isStable defaults

Data loss: old single-counter participants lose saves (feature didn't work,
no real state to preserve). User confirmed acceptable.

Tests:
- turn.deathsave.test.js: RED-then-GREEN, 3-success stable, 3-fail dead,
  independent tracking, new signature
- Updated 6 callers across characterization/combat/dead-skip/logging/scenario
- Logs UI tests: new title selectors (Success N / Fail N)

243 tests green.

shared/tests/turn.dead-skip.test.js

@@ -56,10 +56,10 @@ describe('unified: death deactivates, dead skipped in rotation', () => {
     // kill b (current = a)
     e = { ...e, ...applyHpChange(e, 'b', 'damage', 100).patch };
     // b is dead: DM can still fire deathSave (manual action)
-    const r = deathSave(e, 'b', 1);
+    const r = deathSave(e, 'b', 'fail', 1);
     expect(r.patch).toBeTruthy();
     const b = r.patch.participants.find(x => x.id === 'b');
-    expect(b.deathSaves).toBe(1);
+    expect(b.deathFails).toBe(1);
   });
 
   // D1 unification: shared now matches App main — death flips isActive=false.