Adds a Delete button to each message card in the staff inbox so staff
can remove spam or dead-end submissions. Confirmation dialog (via
JS confirm()) prevents accidental deletions. Implementation:
- POST handler: DELETE FROM contacts WHERE id = ? (parameterized)
- .btn--danger CSS variant (red-tinted, matches dark theme)
- Delete button rendered in every message footer alongside existing
Mark as read action
https://claude.ai/code/session_015wpwmheufcxkBuXivrSHhd
132d2c3a34