fix(import): "fill my station fields" fills the station callsign too

STATION_CALLSIGN was the one field the option deliberately skipped, on the
grounds that stamping the active call could re-route a mixed-call log.

That protected nothing. The same option already writes this profile's grid,
rig, antenna, city and postal address onto every record it finds blank — it
has assumed "this log is mine" long before it reaches the callsign. And the
thing that actually keeps a multi-op log intact is that a record CARRYING a
station callsign is never touched, which has always been true and still is.
Withholding it only meant the option quietly failed on the one field an
operator goes and checks afterwards, leaving imported QSOs with no station
call at all — invisible in the ADIF they export, and unroutable for LoTW
and Club Log.

Counted and logged: "did it fill the callsign?" is the first question after
an import, and the log is where it gets answered.

changelog.json

@@ -3,10 +3,12 @@
     "version": "0.26.0",
     "date": "",
     "en": [
-      "Club Log uploads are now identified as OpsLog. They were credited to another station's application key, which took the blame for them."
+      "Club Log uploads are now identified as OpsLog. They were credited to another station's application key, which took the blame for them.",
+      "ADIF import: \"fill my station fields\" now fills the station callsign too, on records that carry none."
     ],
     "fr": [
-      "Les envois Club Log s’identifient désormais comme OpsLog. Ils étaient attribués à la clé applicative d’une autre station, qui en portait la responsabilité."
+      "Les envois Club Log s’identifient désormais comme OpsLog. Ils étaient attribués à la clé applicative d’une autre station, qui en portait la responsabilité.",
+      "Import ADIF : « remplir mes champs station » renseigne aussi l’indicatif de station, sur les enregistrements qui n’en portent pas."
     ]
   },
   {