Tasks

• [x] Add failing regression tests for scan editing and card/delete interactions.
• [x] Extend PATCH validation and safely relink shared targets.
• [x] Reuse ScanForm for editing from dashboard cards and scan details.
• [x] Fix card navigation and delete pending/error handling.
• [x] Regenerate API types and update architecture/checklist documentation.
• [x] Pass formatting, lint, type, and automated test checks.

Verified: task test (469 backend and 220 frontend tests passed; 6 opt-in tests skipped), task lint, task check, task api:check, and task snapshot:check (48 views). Generated DOM snapshots are excluded from whitespace trimming to preserve literal whitespace. Visual evidence: desktop editor, mobile editor, and delete failure.

Calendar integration preserves checkout anchoring and duration presets when editing saved scans. Both the creation-calendar and editing regression suites are retained, including an edited check-in advancing checkout by the minimum stay.