Make feedback anonymity mode discoverable

[uzayer]

The feedback composer currently toggles user-attributed versus anonymous submission when the identity control is clicked, but the affordance is not obvious.

Add a clear visual indicator and explanatory tooltip/copy beside the feedback identity control (for example, an incognito icon or explicit anonymous toggle) so users can intentionally choose anonymous feedback.

Acceptance criteria:

• The current attribution mode is visible before submitting.
• The control has an accessible label and clear tooltip/copy explaining the action.
• Switching modes visibly confirms the new state.
• The submit payload continues to honor the selected mode.