Adds a 'Sync now' button below the pending operations list in the
dialog, allowing users to manually trigger a sync directly from the
dialog.
## Changes
- Added new props to `PendingOperationsDialog`: `onSyncNow`,
`syncStatus`, and `isOnline`
- Added a button at the bottom of the dialog that triggers the sync
process
- Button shows loading state with spinning icon while syncing
- Button is disabled when offline or when sync is already in progress