feat(hamqth): QSO upload to the HamQTH logbook — the 8th external service

qso_realtime.php with the account's callbook credentials (which the
external-services config falls back to when its own are blank), one ADIF
record per QSO, prg=OpsLog. HTTP status IS the answer: 200 saved, 400
rejected (a duplicate counts as delivered, like HRDLog's insert 0), 403
credentials. Sent-state lives in APP_OPSLOG_HAMQTH_SENT extras like
HAMLOG.online — ADIF names no HamQTH field. Auto-upload on log, on-close
batch, right-click Send to, QSL Manager backlog, and a Test button that
authenticates against the callbook login, which cannot touch the log.

Fixes a real mis-route on the way: manual 'Send to HAMLOG.online' had no
branch in runManualUpload and fell through to QRZ.com — the selection was
uploaded to the wrong service with the QRZ key. Both extras-stamped
services now have their own branch.

frontend/src/components/QSLManagerModal.tsx

@@ -42,6 +42,7 @@ const SERVICES = [
   { v: 'eqsl',    label: 'eQSL.cc' },
   { v: 'lotw',    label: 'LoTW' },
   { v: 'hamlog',  label: 'HAMLOG.online' },
+  { v: 'hamqth',  label: 'HamQTH' },
   { v: 'pota',    label: 'POTA hunter log' },
   { v: 'paper',   label: 'Paper QSL' },
 ];