feat(hamlog): mark an already-uploaded log through bulk edit

A log sent to hamlog.online by hand — an ADIF exported from OpsLog and dropped
on their site — had no way of being marked as sent afterwards. The QSL Manager
then listed every one of those contacts as backlog and offered to upload them a
second time.

Both HAMLOG keys join the bulk-editable extras, so a selection (or the whole
log) can be stamped in one pass. They are DATES rather than Y/N flags because
that is the shape the sent stamp already uses: the QSL Manager's backlog asks
whether the key is present, and a date also says when it went.

The test pins that they are reachable through the extras path and NOT offered as
columns — a mapping claiming both would write to a table that has neither.

frontend/src/components/BulkEditModal.tsx

@@ -48,6 +48,12 @@ const FIELDS: FieldDef[] = [
   { id: 'clublog_sent_date', label: 'bulk.fClublogSentDate', group: 'QSL / upload', kind: 'date' },
   { id: 'hrdlog_sent',       label: 'bulk.fHrdlogSent',      group: 'QSL / upload', kind: 'status' },
   { id: 'hrdlog_sent_date',  label: 'bulk.fHrdlogSentDate',  group: 'QSL / upload', kind: 'date' },
+  // HAMLOG.online: no promoted column, written into extras_json (see
+  // qso.bulkEditableExtras). Free text rather than a Y/N status because the
+  // value carries the DATE it went — which is what the QSL Manager's backlog
+  // and the row colours both read.
+  { id: 'hamlog_sent',       label: 'bulk.fHamlogSent',      group: 'QSL / upload', kind: 'date' },
+  { id: 'hamlog_rcvd',       label: 'bulk.fHamlogRcvd',      group: 'QSL / upload', kind: 'date' },
   // My station / operator
   { id: 'station_callsign', label: 'bulk.fStationCall',  group: 'My station', kind: 'text', upper: true },
   { id: 'operator',         label: 'bulk.fOperator',     group: 'My station', kind: 'text', upper: true },