fix: guard destructive backup restore actions

[kunihir0]

Summary

• Require two confirmations before wipe restore.
• Prevent overlapping restore, retry, merge, acknowledgment, and import actions.
• Bind merge conflicts to the exact analyzed backup.
• Add focused presentation guard tests.

Validation

• 78 backup tests passed.
• iOS 15.4 build passed.
• Changed-file SwiftLint passed with zero violations.
• Code review: APPROVE.
• Architecture review: CLEAR.

Repository-wide lint still has 20 pre-existing out-of-scope violations.