Admin can now open a message via a per-row "View" page (which stamps
read_at the first time it's opened), see a sortable Read column on the
list instead of the raw message text, and soft-delete messages via a
Delete button on both the list and detail view. Deleted messages are
excluded from the default list so it doesn't pile up over time.
Adds a public /contact page (name/email/message, protected by the same
reCAPTCHA v3 setup used on registration) that persists submissions to
a new contact_message table, plus a Contact section in the admin panel
to read them. Linked from the site footer.
Frank