feat(explorer): Warm Storage dataset table on the service page

### Description

On `/console/services/[operator]` when the operator is Warm Storage, show the payer's datasets: id, provider, size, last write, monthly spend, and a link out to PDP Explorer for proving status.

Cut from the POC after PM review and not wanted here: retrieval badge, funded-until column, per-dataset runway (funding is account-level, per-dataset runway is a fiction).

### Expected behavior

Datasets sorted by last write ascending by default. Empty state for a payer with rails but no datasets. Loading and error states match the rest of the console.

### Additional context

Parent: #460. Depends on #462. POC column definitions in #365 `WarmStorageSection/data/columnDefinitions.tsx` are the starting point, minus the cut columns.

Merges alone: section renders only when the operator is Warm Storage and the `DataSet` query returns rows; hidden otherwise.

Start at the /console/services/[operator] service page and use WarmStorageSection/data/columnDefinitions.tsx from #365 as the reference. Check the DataSet query and the existing console loading, error, and empty states before implementing the section. Done means Warm Storage shows the specified dataset columns sorted by last write, while non-Warm Storage and empty or loading/error cases behave as described.

Written by the indexing model from the issue text.