Operators want a place to jot observations that aren't captured by
the structured fields — weather anecdotes, propagation mode
commentary, equipment details, band conditions. Add a text column
on contacts plus the two ingest paths users submit through:
* /submit single-contact form gets a 3-row textarea under the
other fields. Optional, max 2000 chars, with a live length cap
via maxlength. Whitespace-only input collapses to NULL so the
column reflects "no notes" rather than an empty string.
* CSV importer recognises a `notes` (or `note`) column via the
existing header_aliases table and flows values straight through
submission_changeset. Sample template gets a matching example
row with embedded commas so the quoted-field round-trip is
exercised on download.
ADIF import and the refinement/refinement-notify paths are out of
scope — users specifically asked for CSV + single-contact. Tests
cover the changeset (accept/blank/over-length), CSV header parsing
(plain + RFC-4180 quoted), and LiveView form submit end-to-end.
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.
