Implement per-wallet buy cooldown countdown display on key detail page #915

Summary

Display a countdown timer on the creator key detail page when the connected wallet is in a buy cooldown period, disabling the buy button until the cooldown expires.

Scope

• Fetch cooldown expiry for connected wallet from contract
• Show countdown timer on buy panel when cooldown is active
• Disable buy button and show remaining time
• Auto-enable buy button when countdown reaches zero
• Clear UI state shown when no cooldown is active

Acceptance Criteria

• Cooldown expiry fetched on wallet connect and key page load
• Countdown timer displays remaining time accurately
• Buy button disabled during active cooldown
• Button re-enables automatically at cooldown expiry
• No cooldown state shows normal buy UI without any timer

ETA

12 hours