[Bug] newly created group does not appear in Miners table until refresh, and action bar becomes non-interactable

### Describe the bug

When using `Add to group` from the `Miners` page, the new group is created successfully, but the `Groups` column does not update until the page is refreshed.

After the same action, the action bar also becomes non-interactable.

### Preconditions

- Be on the `Miners` page
- Have at least one miner available to select

### Steps to reproduce

1. Navigate to `Miners`
2. Select all checkboxes
3. Click `More`, then `Add to group` in the action bar
4. Enter a group name
5. Click `Save` to confirm the group name

### Expected behavior

- All selected miners show the newly added group in the `Groups` column
- If the table shows `X groups`, that count increases by one as expected
- The action bar remains interactable, or the miners are deselected and the action bar disappears

### Proto Fleet version

`nightly-20260703-a7b00e867a12-13-g04a0c8c5-dirty`

### Environment

- OS: macOS
- Browser: Chrome

https://github.com/user-attachments/assets/1ff9bf4c-75d7-4233-8661-1759e1da661d

Start at the Miners page and trace the Add to group flow from the More action bar through Save. Reproduce with selected miners, then verify that the Groups column updates immediately and that the action bar remains usable or disappears after deselection.

Written by the indexing model from the issue text.