fix: row selection leaks across pages in dataset and file list tables (#13668)

### What problem does this PR solve?

When using pagination in the Dataset file list or File Manager,
selecting row N on page 1 would incorrectly cause row N on page 2 (and
subsequent pages) to also appear selected. This is a state pollution
bug.

### Root Cause

TanStack React Table defaults to using array indices (0, 1, 2...) as
`rowSelection` keys. With server-side (manual) pagination, each page's
rows start from index 0, so a selection like `{2: true}` on page 1 also
matches index 2 on every other page.

### Fix

- Added `getRowId: (row) => row.id` to `useReactTable` in both
`DatasetTable` and `FilesTable`, so selection state is keyed by unique
document/file IDs instead of positional indices.
- Updated the `useSelectedIds` helper to support ID-based selection keys
while maintaining backward compatibility with index-based keys.

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

### Files Changed

| File | Change |
|------|--------|
| `web/src/pages/dataset/dataset/dataset-table.tsx` | Added `getRowId`
to table config |
| `web/src/pages/files/files-table.tsx` | Added `getRowId` to table
config |
| `web/src/hooks/logic-hooks/use-row-selection.ts` | Updated
`useSelectedIds` to handle ID-based selection |