Build sender review step before sealing with final payload summary

[nottherealalanturing]

Description

Sealing should feel deliberate. A review screen improves clarity around recipient, unlock date, attachment, and gift settings.

Scope

• Add review page or modal before final seal
• Show validation checklist for missing fields
• Surface warning for irreversible action
• Review key files: web composer/detail routes

Acceptance Criteria

• Sender sees all key capsule fields before sealing
• Review flow blocks invalid payloads
• Final seal action is only available from completed review

Dependencies

Blocked by: Phase 1 seal flow issue
Blocked by: Image upload issues

Stack

Next.js