feat(chat): scenario-based training — choice of channel/Situation + realistic per-turn evaluation

Backend:
- Channel/initiation now driven by a SCENARIO chosen at chat start, not baked into the
  persona: social (customer opens), f2f_call (seller must open, proactive), recontact
  (customer re-contacts after 1-3 months).
- /chat/start accepts {scenario}; session stores scenario + internal{turns,score}.
- persona_reply takes scenario + adapts tone; system-role transcript entries are fed to
  the persona as hidden scene notes.
- JUDGE updated for realism: good response can WIN even in hard/tough-text scenarios;
  long/no-close chats (turns >~12) lose; pushy/ignoring-need loses. Efficiency rewarded.

Frontend:
- Scenario picker before chat (choose Social / Face-to-face-call / Re-contact).
- Chat thread renders role=system as a centered time-lapse/scene note.
- Choose-scenario i18n (EN+TH).
Rebuilt dist.

backend/scripts/test_scenario.py

@@ -0,0 +1,79 @@
+"""Test: scenario-based chat start (scenario determines who opens)."""
+import os, sys, tempfile, warnings
+from pathlib import Path
+
+warnings.filterwarnings("ignore")
+BACKEND = str(Path(__file__).resolve().parents[1])
+sys.path.insert(0, BACKEND)
+
+from app.factory import create_app
+from app.config import Config
+
+td = tempfile.mkdtemp()
+Config.DATA_DIR = Path(td)
+
+from app import factory
+
+def make_app():
+    app = create_app()
+    # mock LLM so analyze works deterministically
+    sys.path.insert(0, BACKEND + "/scripts")
+    from mock_llm import MockLLM
+    app.extensions["llm"] = MockLLM()
+    return app
+
+app = make_app()
+C = app.test_client()
+
+def login(u, p):
+    return C.post("/api/auth/login", json={"username": u, "password": p}).get_json()["token"]
+
+AT = login("admin", "1234")
+AH = {"Authorization": f"Bearer {AT}"}
+C.post("/api/auth/setup", headers=AH, json={"username": "admin", "email": "a@b.co", "password": "newpass"}).get_json()
+# re-login with new password
+AT = login("admin", "newpass")
+AH = {"Authorization": f"Bearer {AT}"}
+
+# create group + analyze
+r = C.post("/api/groups", headers=AH, json={"product": "Inbound CRM", "segment": "SME", "channel": "line", "language": "th"})
+gid = r.get_json()["group"]["id"]
+C.post(f"/api/groups/{gid}/analyze", headers=AH)
+personas = C.get(f"/api/groups/{gid}/personas", headers=AH).get_json()["personas"]
+# build a ready group accepted by trainees
+C.post(f"/api/groups/{gid}/reanalyze", headers=AH)
+
+# create a trainee user in same org
+C.post("/api/admin/users", headers=AH, json={"username": "t1", "name": "T", "password": "pppp", "role": "user"})
+T = login("t1", "pppp")
+TH = {"Authorization": f"Bearer {T}"}
+
+pid = personas[0]["id"]
+
+# social -> customer opens
+r = C.post(f"/api/chat/{gid}/personas/{pid}/chat/start", headers=TH, json={"scenario": "social"})
+assert r.status_code == 200, r.get_json()
+s = r.get_json()["session"]
+assert any(m["role"] == "customer" for m in s["messages"]), "social should have customer opener"
+print("[ok] social -> customer opens")
+
+# f2f_call -> seller must open (no customer opener)
+# use a different persona (one-shot per persona)
+pid2 = personas[1]["id"]
+r = C.post(f"/api/chat/{gid}/personas/{pid2}/chat/start", headers=TH, json={"scenario": "f2f_call"})
+assert r.status_code == 200, r.get_json()
+s2 = r.get_json()["session"]
+assert not any(m["role"] == "customer" for m in s2["messages"]), "f2f should NOT have customer opener"
+assert any(m["role"] == "system" for m in s2["messages"]), "f2f should have a scenario system note"
+print("[ok] f2f_call -> seller must open (system note present)")
+
+# recontact -> system preamble about time-lapse + customer opens
+pid3 = personas[2]["id"]
+r = C.post(f"/api/chat/{gid}/personas/{pid3}/chat/start", headers=TH, json={"scenario": "recontact"})
+assert r.status_code == 200, r.get_json()
+s3 = r.get_json()["session"]
+assert any(m["role"] == "customer" for m in s3["messages"]), "recontact should open w/ customer"
+assert any(m["role"] == "system" and "เดือน" in m["text"] for m in s3["messages"]), "recontact system note (months)"
+print("[ok] recontact -> time-lapse system note + customer opens")
+
+print("ALL SCENARIO TESTS PASSED")