fix: raise /api/domains limit cap from 500 to 5000

FastAPI was returning 422 for limit=5000, causing d.results to be
undefined and the table to show 0 results. Matches /api/enriched cap.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/beauty_main.py

@@ -132,7 +132,7 @@ async def get_index_status():
 async def domains(
     tld: str = Query(None),
     page: int = Query(1, ge=1),
-    limit: int = Query(100, ge=1, le=500),
+    limit: int = Query(100, ge=1, le=5000),
     live_only: bool = Query(False),
     alpha_only: bool = Query(False),
     no_sld: bool = Query(False),