fix: reduce tokens limit to 20 per review

src/backend/app/api/config.py

@@ -1,13 +1,19 @@
 from fastapi import APIRouter
 
+from ..core.config import get_settings
+from ..services.ave import AveCloudClient
+
 router = APIRouter()
 
 
 @router.get("/chains")
 def get_chains():
-    return {"chains": []}
+    return {"chains": ["bsc"]}
 
 
 @router.get("/tokens")
-def get_tokens():
-    return {"tokens": []}
+async def get_tokens():
+    settings = get_settings()
+    client = AveCloudClient(api_key=settings.AVE_API_KEY, plan=settings.AVE_API_PLAN)
+    tokens = await client.get_tokens(chain="bsc", limit=20)
+    return {"tokens": tokens}