feat(chat): persona decides to buy/walk — auto-finish + tolerance (temper) + resume

The conversation now ENDS when the persona makes a decision (option C), not when the
trainee clicks a button:
- persona_id replies carry {reply, decision(none/buy/walk), mood}; when decision is
  buy/walk the session auto-finishes (won/lost) with a debrief that reveals latent
  details + per-turn 'turning points'.
- personas have a tolerance (1-5, 'temper'): impatient personas walk away fast after
  poor answers (fed via internal.misses on mood<=-1); tough 'wrong text' cases can
  still be won by a strong, gentle response (judge realism).
- trainee 'Finish' button removed; if they leave mid-chat an active session is resumed
  via /chat/resume (continue, not restart). One-shot lock still enforced once decided.
- mock/tests updated: persona deciding buy -> send auto-finishes won.
Rebuilt dist.

frontend/src/api/index.js

@@ -48,6 +48,7 @@ export const api = {
   getPersona: (gid, pid) => request('GET', `/api/groups/${gid}/personas/${pid}`),
   updatePersona: (gid, pid, b) => request('PUT', `/api/groups/${gid}/personas/${pid}`, b),
   chatStart: (gid, pid, scenario) => request('POST', `/api/chat/${gid}/personas/${pid}/chat/start`, scenario || {}),
+  chatResume: (gid, pid) => request('GET', `/api/chat/${gid}/personas/${pid}/chat/resume`),
   chatSend: (gid, pid, text) => request('POST', `/api/chat/${gid}/personas/${pid}/chat/send`, { text }),
   chatFinish: (gid, pid) => request('POST', `/api/chat/${gid}/personas/${pid}/chat/finish`),
   mySessions: () => request('GET', '/api/chat/sessions'),