Add a Configure Tools action to the Chat permissions picker

## Feature Request

The Chat permissions picker does not provide a direct way to configure terminal auto-approval rules. Users must manually open Settings and search for `chat.tools.terminal.autoApprove`.

## Proposed Solution

Add a gear icon button labeled **Configure tools** to the **Default permissions** row.

When activated, the button should:

- Close the permissions picker.
- Open the visual Settings editor filtered to `chat.tools.terminal.autoApprove`.
- Be accessible through keyboard navigation and screen readers.
- Use localized label and tooltip text.

The action should only appear for the built-in permission options and must not affect extension-contributed permission entries.

## Acceptance Criteria

- A Configure tools gear appears on the Default permissions row.
- Activating it opens the Terminal: Auto Approve setting directly.
- Existing permission selection, sandboxing, and Learn more actions continue to work.
- The action is covered by unit tests and accessibility-help tests.