Render Drops sources as a Noora table

The Drops operations page (/ops/drops) now lists sources using the standard Noora table pattern instead of a custom card-row layout. The source list shows columns for source, status, and last poll time, with sync, enable/disable, and remove actions moved into a compact row action menu. The empty state also uses the table empty-state slot, providing a layout consistent with other table surfaces in Hive.