Card: unlimited approve has no acknowledgement checkbox (Stage-3 spec promised one)

[temrjan]

What

The Slice-1b spec (Stage 3, C-PR-1) promised the confirmation card for an unlimited
ERC-20 approval would carry three things: UNLIMITED, an acknowledgement checkbox,
and the per-transaction PIN. The shipped console (v0.1.0) has two of the three:

• HIGH RISK: unlimited_approval (bold) — src/ui.rs
• decoded_call.method: approve, spender, amount: UNLIMITED (bold)
• High-risk approval — enter your PIN: prompt with a masked entry

There is no checkbox anywhere in ui.rs / app.rs.

Why this issue exists

Found during the Stage-6 end-to-end acceptance of the shipped wallet image (repo mcp,
tests/e2e). The acceptance suite asserts what actually ships — risk banner, UNLIMITED
line, and the PIN gate — and those all hold: a bare y on a high-risk card sends nothing,
it opens the PIN prompt (app.rs::on_approve), and the server independently refuses a
pin-less approve with pin_required.

So the protection is in place; what is missing is the second deliberate act the
Stage-3 spec asked for. Arguably the PIN is the stricter gate — but the deviation from a
ratified spec should be decided in the open, not quietly inherited.

Options

1. Accept the shipped design and amend the Stage-3 spec (PIN supersedes the checkbox).
2. Add the checkbox before the PIN prompt on high_risk cards (a [ ] I understand …
   toggle that must be checked before the PIN entry unlocks).

Decision is the Captain's; this issue exists so it does not evaporate.