v6 Phase C: Cookbook diversifiziert + 'Beste Wahl' hervorgehoben

- recipes.py: best-in-class je Use-Case, herstelleruebergreifend (Qwen3-Coder, Gemma 3,
  Mistral Small, DeepSeek-R1, Qwen3-VL) + neue Kategorie 'Nachdenken & Logik'.
- recipes-Endpoint: recommended_id = reichstes Setup das komplett passt.
- cookbook.js + CSS: 'Beste Wahl fuer dein System' (Rahmen + Badge).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

routers/cookbook.py

@@ -134,7 +134,10 @@ def recipes():
             if _FIT_ORDER[fit["level"]] > _FIT_ORDER[worst]:
                 worst = fit["level"]
         out.append({**r, "models": models, "fit_level": worst})
-    return {"recipes": out, "sys_ram_gb": round(ram_gb, 1)}
+    # „Beste Wahl": das reichste Setup, das komplett auf die Hardware passt.
+    fitting = [r for r in out if r["fit_level"] != "too_tight"]
+    rec = max(fitting, key=lambda r: len(r["models"]), default=None) if fitting else None
+    return {"recipes": out, "sys_ram_gb": round(ram_gb, 1), "recommended_id": rec["id"] if rec else None}
 
 
 @router.post("/install-recipe")