The email-step Send button disabled on any running cooldown, so a merchant
who mistyped their address was locked out of sending to the corrected one
for the rest of the 60s window — a guard the server never had: request_code
enforces the cooldown per address (SD-0001 INV-3 -> PUC-2c).
Track which address the running cooldown belongs to (cooldownFor) and gate
the email-step button through cooldownAppliesTo(), which blocks only while
the countdown runs AND the input normalizes (strip+lowercase, mirroring
normalize_email / INV-2) to that address. Same address still shows the
honest 'Resend in Ns'; any other address sends immediately. The code-step
resend is unchanged. Verified in the live UI (wrong address -> Wrong
address? -> corrected address sends at once).
package-lock.json: sync recorded version with package.json (0.4.0).
Closes#20
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>