feat(idea): create group auto-generates personas; channel removed; product->product/idea

Per product-idea focus:
- GroupBuilder: 'สินค้า/บริการ/ไอเดีย' label; removed the channel select (channel is now
  chosen at chat time as a scenario, not at persona create). Create now auto-runs analyze
  so personas are generated immediately (no separate Analyze button).
- GroupEdit: analyze button becomes 'สร้างบุคคลต้นแบบเพิ่มเติม' which APPENDS more personas
  (backend analyze?append=true reuses sales kit + keeps existing instead of replacing).
- i18n product label updated.
- User-journey test asserts append adds personas (15->30) and existing kept.
All 9 backend suites pass. Rebuilt dist.

backend/app/api/group_routes.py

@@ -170,9 +170,13 @@ def list_groups():
 @require_auth
 @require_roles("admin")
 def analyze_group(gid: str):
-    """Run analysis: sales kit + 15 personas. Synchronous for v1 (replaces gen)."""
+    """Run analysis: sales kit + 15 personas. Synchronous for v1 (replaces gen).
+
+    ?append=true generates MORE personas and appends to existing ones instead of
+    replacing them (used by 'create more personas')."""
     s = _stores()
     group = _get_owned_group(s, gid)
+    append = request.args.get("append") == "true"
 
     inp = group.get("input", {})
     if not s["llm"]:
@@ -181,20 +185,33 @@ def analyze_group(gid: str):
     from ..services.analyzer import Analyzer
     from ..services.persona_generator import PersonaGenerator
 
-    s["groups"].update(gid, status="analyzing", error=None)
+    # If appending, reuse the existing sales kit; else re-run the full analysis.
+    sales_kit = group.get("sales_kit")
+    if not append or not sales_kit:
+        s["groups"].update(gid, status="analyzing", error=None)
+        try:
+            sales_kit = Analyzer(s["llm"]).analyze(
+                product=inp.get("product", ""),
+                segment=inp.get("segment", ""),
+                description=inp.get("description", ""),
+                file_text=inp.get("file_text", ""),
+                channel=inp.get("channel", "facebook"),
+            )
+        except Exception as exc:
+            s["groups"].update(gid, status="failed", error=str(exc))
+            raise ApiError(f"analysis failed: {exc}", 500)
+        s["groups"].update(gid, sales_kit=sales_kit, status="ready", error=None)
+
+    existing = []
+    if append:
+        existing = s["groups"].get_or_none(gid).get("personas", []) or []
     try:
-        sales_kit = Analyzer(s["llm"]).analyze(
-            product=inp.get("product", ""),
-            segment=inp.get("segment", ""),
-            description=inp.get("description", ""),
-            file_text=inp.get("file_text", ""),
-            channel=inp.get("channel", "facebook"),
-        )
         personas = PersonaGenerator(s["llm"]).generate(
             sales_kit=sales_kit,
             language=inp.get("language", "th"),
             channel=inp.get("channel", "facebook"),
         )
+        personas = existing + personas
     except Exception as exc:
         s["groups"].update(gid, status="failed", error=str(exc))
         raise ApiError(f"analysis failed: {exc}", 500)