Revoking a proposal token in the terminal asks first: `x` names the child, `y` revokes, `n` or esc keeps it #7949

Intent: a revoke cuts a child forge off until it is handed a new token, so the terminal asks before it does it, as the boards screen does before a delete.

Today src/tui/screens/proposal_tokens.ts calls revokeProposal the moment x is pressed on a row.

Done looks like:

• [ ] x on a token opens confirmScreen (from src/tui/screens/common.ts, yesNo: true) titled "Revoke the token for <child>?" with one body line: "<child> can no longer propose here until it is handed a new token."
• [ ] y (or the Revoke button) calls revokeProposal and the head line reads "<child>: revoked." as today; n or esc revokes nothing and the token is still listed.
• [ ] x on an empty list does nothing, as today.
• [ ] test/tui-proposal-tokens.test.ts: the existing x test presses y after x; a new test presses x then n and proves the token is still in listProposals. The new test fails without the change.
• [ ] bun test test/tui-proposal-tokens.test.ts passes.

Files: src/tui/screens/proposal_tokens.ts, test/tui-proposal-tokens.test.ts Risks: none beyond the screen; the action's rules (actions/proposal_tokens.ts) are unchanged. Brief: a builder who knows the terminal screens.

Parked by the crew: the check stayed red through 2 automatic tries (pull #7958 closed). Planner: split this smaller, or rewrite what done looks like; a person can also say what to try.