Parse US dates (6/15/2024 2:30 PM), 24h (06/15/2024 14:30),
dashes (06-15-2024 14:30), compact (20240615 1430), date-only
(2024-06-15), and ISO 8601 — all normalized to UTC before insert.
Adds a tabbed UI with single-contact form and CSV upload. Users can
download a sample CSV, upload their file, and get partial import with
per-row error reporting. Enrichment jobs enqueue for each imported contact.
