fix: hand-corrected CQ/ITU zones came back wrong at every restart

The profile's MY_* metadata is derived from the callsign through cty.dat, and the
effect that derives it ran on every load — so opening the settings counted as
"the source changed" and overwrote whatever the operator had typed. Reported by
an operator in CQ 4 / ITU 4 handed 5 and 9: he corrected them, and each restart
put 5 and 9 back.

cty.dat gives the zones of the ENTITY, and a large country spans several, so the
automatic value cannot be treated as authoritative — it is a starting point. A
load now fills only fields that are EMPTY; a recompute that overwrites happens
only when the callsign or grid itself changes, which is the case the derivation
exists for.

The load-vs-edit distinction is a ref holding the profile id the values were last
derived from — first sight of a profile is a load.

changelog.json

@@ -1,4 +1,14 @@
 [
+  {
+    "version": "0.21.9",
+    "date": "2026-07-28",
+    "en": [
+      "CQ and ITU zones you correct by hand in your profile stay corrected. They are derived from cty.dat, which gives the zones of the whole entity — in a country spanning several, the automatic value is wrong and it came back at every restart. They now only fill in when empty, and recompute when the callsign or grid changes."
+    ],
+    "fr": [
+      "Les zones CQ et ITU corrigées à la main dans votre profil restent corrigées. Elles proviennent de cty.dat, qui donne les zones de l'entité entière — dans un pays qui en couvre plusieurs, la valeur automatique est fausse et revenait à chaque redémarrage. Elles ne se remplissent désormais que si le champ est vide, et se recalculent quand l'indicatif ou le locator change."
+    ]
+  },
   {
     "version": "0.21.8",
     "date": "2026-07-28",