fix(ui): no raw JSON on Training list, pain no longer [object Object], add Chat button on GroupEdit, drop facebook/line from persona

- list_groups returns lightweight summaries (id/title/status/persona_count + product) —
  never the full personas array, so Training no longer shows a long JSON blob.
- PersonaForm toLines extracts .description/.text from pain/objection objects (fixes
  '[object Object]'); save re-wraps pains as {description}.
- GroupEdit persona cards get a 'แชท' (MessageSquare) button so you can start chatting
  right where you land after creating (chat was only on Personas page before).
- channel: default neutral 'social', removed facebook/line validation + removed from
  revealable_view (scenario now sets the tone, not fb/line).
All 9 backend suites pass. Rebuilt dist.

backend/app/services/store.py

@@ -23,7 +23,7 @@ def ensure_persona_shape(p: dict[str, Any]) -> dict[str, Any]:
         "name": p.get("name", ""),
         "tier": p.get("tier", p.get("intent_tier", "B")),
         "initiation_mode": p.get("initiation_mode", "customer"),  # customer | seller
-        "channel": p.get("channel", "facebook"),                  # facebook | line
+        "channel": p.get("channel", "social"),                  # internal tone hint (scenario overrides)
         # revealable
         "profession": p.get("profession", ""),
         "age_group": p.get("age_group", ""),
@@ -47,13 +47,11 @@ def ensure_persona_shape(p: dict[str, Any]) -> dict[str, Any]:
         "tolerance": p.get("tolerance", 3),    # misses before this persona walks away (temper)
         "notes": p.get("notes", ""),
     }
-    # validate
+    # validation
     if base["tier"] not in DEFAULT_TIERS:
         base["tier"] = "B"
     if base["initiation_mode"] not in ("customer", "seller"):
         base["initiation_mode"] = "customer"
-    if base["channel"] not in ("facebook", "line"):
-        base["channel"] = "facebook"
     return base
 
 
@@ -63,7 +61,6 @@ def revealable_view(p: dict[str, Any]) -> dict[str, Any]:
         "id": p.get("id"),
         "name": p.get("name"),
         "tier": p.get("tier"),
-        "channel": p.get("channel"),
         "initiation_mode": p.get("initiation_mode"),
         "profession": p.get("profession"),
         "age_group": p.get("age_group"),