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/services/persona_generator.py

@@ -8,7 +8,8 @@ from ..llm import LLMClient
 from .persona_prompts import PERSONA_SYSTEM
 
 TIERS = ["A", "B", "C"]
-PER_TIER = 5
+PER_TIER = 5      # 5 per tier = 15 total
+TARGET = 15       # total personas the system generates (no "add more" button needed)
 
 
 class PersonaGenerator:
@@ -20,7 +21,7 @@ class PersonaGenerator:
         *,
         sales_kit: dict[str, Any],
         language: str = "en",
-        channel: str = "facebook",
+        channel: str = "social",
     ) -> list[dict[str, Any]]:
         kit_json = json.dumps(sales_kit, ensure_ascii=False)[:12000]
         lang_name = "Thai" if language == "th" else "English"
@@ -46,13 +47,15 @@ class PersonaGenerator:
                 PERSONA_SYSTEM, prompt, temperature=0.8, max_tokens=14000
             )
             personas = result.get("personas") or []
-            if (isinstance(personas, list) and len(personas) >= 15) or attempt >= 3:
+            if (isinstance(personas, list) and len(personas) >= TARGET) or attempt >= 3:
                 break
         if not isinstance(personas, list) or not personas:
             raise ValueError("persona generator returned no personas")
 
         normalized, counts = [], {"A": 0, "B": 0, "C": 0}
         for idx, p in enumerate(personas, start=1):
+            if len(normalized) >= TARGET:
+                break  # already reached 20 total
             if not isinstance(p, dict):
                 continue
             tier = p.get("tier", p.get("intent_tier"))
@@ -86,7 +89,6 @@ class PersonaGenerator:
 
         if len(normalized) < 8:
             raise ValueError(f"expected ~15 personas, generated only {len(normalized)}")
-        # NOTE: if we're short of 15 (real LLMs occasionally return 14/13), we ACCEPT what we
-        # got rather than crashing the whole analyze — the caller/UI can top up with
-        # "create more personas". A retry loop lives in generate().
+        # NOTE: if we're short of 15 (real LLMs occasionally return 14), we ACCEPT what we
+        # got rather than crashing the whole analyze — with TARGET=15 there's normally no gap.
         return normalized