Add /api/public/availability endpoint + bot stock-check instructions

main.py

@@ -205,6 +205,16 @@ def public_pricing(db: Session = Depends(get_db)):
     ]
 
 
+@app.get("/api/public/availability")
+def public_availability(db: Session = Depends(get_db)):
+    """Returns which tiers are in stock — no auth, super simple."""
+    services = db.query(Service).order_by(Service.sort_order).all()
+    return [
+        {"name": s.name, "available": s.active, "sell_price": s.sell_price}
+        for s in services
+    ]
+
+
 @app.get("/api/public/services/{service_id}")
 def public_service_detail(service_id: int, db: Session = Depends(get_db)):
     svc = db.query(Service).filter(Service.id == service_id, Service.active == True).first()