fix(scenario): recontact chats normally first then re-engages mid-chat; channel default=social; remove 'add more' button (15 personas auto)

- recontact persona now opens as a NORMAL customer (no 'I asked before' in the opening);
  the mid-chat time-lapse system note (turn 2) makes them re-engage warmer instead.
- channel default changed facebook->social everywhere (create/analyze/store/simulator/me).
- 15 personas auto-generated (TARGET=15); removed the 'สร้างบุคคลต้นแบบเพิ่มเติม' button/guide.
All 9 backend suites pass. Rebuilt dist.

backend/app/api/group_routes.py

@@ -139,7 +139,7 @@ def create_group():
             "product": product,
             "segment": (data.get("segment") or ""),
             "description": (data.get("description") or ""),
-            "channel": (data.get("channel") or "facebook"),
+            "channel": (data.get("channel") or "social"),
             "language": (data.get("language") or "th"),
             "files": saved_files,
             "file_text": file_text[:60000],
@@ -209,7 +209,7 @@ def analyze_group(gid: str):
                 segment=inp.get("segment", ""),
                 description=inp.get("description", ""),
                 file_text=inp.get("file_text", ""),
-                channel=inp.get("channel", "facebook"),
+                channel=inp.get("channel", "social"),
             )
         except Exception as exc:
             s["groups"].update(gid, status="failed", error=str(exc))
@@ -223,7 +223,7 @@ def analyze_group(gid: str):
         personas = PersonaGenerator(s["llm"]).generate(
             sales_kit=sales_kit,
             language=inp.get("language", "th"),
-            channel=inp.get("channel", "facebook"),
+            channel=inp.get("channel", "social"),
         )
         personas = existing + personas
     except Exception as exc:

backend/app/api/me_routes.py

@@ -74,7 +74,7 @@ def _personal_group(s, actor) -> dict:
         g["id"],
         status="ready",
         owner_user_id=actor["id"],
-        input={"channel": "facebook", "language": "th"},
+        input={"channel": "social", "language": "th"},
         sales_kit={"productName": "personal practice", "valueProps": [], "features": []},
     )
     return s["groups"].get(g["id"])