fix(entity): show the QSO's own entity, and date the ClubLog exception

Two faults behind one screenshot: 3Y0K, recorded in the log as Bouvet Island,
showing the Antarctica matrix.

SELECTING A QSO now shows what that QSO records. The panel asked WorkedBefore
with no DXCC hint, and a hint of zero makes the backend resolve the entity from
cty.dat and the ClubLog exceptions AS THEY ARE TODAY — right for a live contact,
wrong for one being looked at in the log. The repo's own "infer from past QSOs"
path never ran, because the hint was no longer zero by the time it got there.
Hence Antarctica, and "5 QSOs with this entity" against "11 with this call":
two different entities, one of them nobody had asked about. The selected row's
dxcc now travels with it and is passed as the hint.

Browsing the log shows what the log says, even where the log is wrong.
Correcting an entity stays a deliberate act — right-click, Update from ClubLog.

BACK-ENTERING A QSO now resolves the exception at the CONTACT'S date. An
exception carries a validity window and a DXpedition's window closes: 3Y0K typed
months later, with the activation's own date in the form, was resolved against
today, matched nothing, and fell back to cty.dat. Both callers pass the date
they already hold — the entry strip's, and in the editor the record's own.

The date is trusted to move the resolution BACKWARDS only. A half-typed
"2026-0" must not send the lookup to the year 20, and a mistyped future date
must not resolve against a window that has not opened; both fall back to now.
Midday rather than midnight, because a window given in whole days is inclusive
of its end date and 00:00 sits exactly on the boundary.

changelog.json

@@ -6,13 +6,17 @@
       "Opening the Awards panel no longer pulls the whole logbook several times at once — a large log briefly took gigabytes of memory.",
       "Awards: the Missing refs button now only appears where it means something — a worldwide award like POTA could only ever answer “nothing found”.",
       "Worked before: a prefixed call like ZA/OE8NDR matched every other visitor to that country instead of that one operator.",
-      "French: seventeen strings were still in English, the whole update panel among them, plus Spot lifetime and Chase new grids."
+      "French: seventeen strings were still in English, the whole update panel among them, plus Spot lifetime and Chase new grids.",
+      "Selecting a QSO shows the entity the QSO records, not one re-derived from its callsign — a 3Y0K contact logged as Bouvet showed the Antarctica matrix.",
+      "Back-entering a QSO resolves the ClubLog exception at the CONTACT’S date, so a DXpedition entered months later gets the entity it had then."
     ],
     "fr": [
       "Ouvrir le panneau Awards ne tire plus plusieurs fois le journal entier en même temps — un gros log occupait brièvement des gigaoctets de mémoire.",
       "Awards : le bouton Réf. manquantes n’apparaît plus que là où il a un sens — un diplôme mondial comme POTA ne pouvait répondre que « aucun manque ».",
       "Déjà contacté : un indicatif préfixé comme ZA/OE8NDR rapprochait tous les autres visiteurs du pays au lieu de ce seul opérateur.",
-      "Français : dix-sept textes étaient restés en anglais, dont tout le panneau de mise à jour, la durée de vie des spots et Chasser les nouveaux locators."
+      "Français : dix-sept textes étaient restés en anglais, dont tout le panneau de mise à jour, la durée de vie des spots et Chasser les nouveaux locators.",
+      "Sélectionner un QSO affiche l’entité que le QSO enregistre, pas une recalculée depuis l’indicatif — un 3Y0K logué Bouvet montrait la matrice Antarctique.",
+      "Saisir un QSO a posteriori résout l’exception ClubLog à la date DU CONTACT : une DXpedition entrée des mois après retrouve l’entité qu’elle avait alors."
     ]
   },
   {