feat: ClubLog Most Wanted rank in the entry band matrix

Opt-in (Settings → General). Shows a "MW #rank" pill next to the DXCC entity
name in the entry-strip band/slot matrix — ClubLog's Most Wanted ranking
(1 = most wanted), personalised to the operator's callsign and refreshed daily.

- internal/clublog/mostwanted.go: fetch mostwanted.php?api=1&callsign=<CALL>
  (rank→DXCC JSON, real User-Agent), invert to dxcc→rank, cache to
  <dataDir>/clublog_mostwanted.json; NeedsRefresh invalidates on callsign change.
- app.go: keyClublogMostWanted setting, a.clublogMW, startup refresh goroutine,
  activeCallsign() helper, and Get/Set/Download bindings mirroring the cty ones.
  WorkedBefore now carries MWRank (qso.WorkedBefore.MWRank) when enabled.
- BandSlotGrid.tsx: MW pill next to the entity name, colour-tiered by rank.
- SettingsModal General: toggle + download button + status, mirroring the
  ClubLog cty-exceptions block.

Also reorganises the changelog: the theme-persistence fix (landed after the
v0.20.11 tag) plus this feature go under a new 0.20.12 entry; 0.20.11 keeps only
what shipped in its binary.

frontend/wailsjs/go/main/App.js

@@ -278,6 +278,10 @@ export function DownloadClublogCty() {
   return window['go']['main']['App']['DownloadClublogCty']();
 }
 
+export function DownloadClublogMostWanted() {
+  return window['go']['main']['App']['DownloadClublogMostWanted']();
+}
+
 export function DownloadConfirmations(arg1, arg2, arg3) {
   return window['go']['main']['App']['DownloadConfirmations'](arg1, arg2, arg3);
 }
@@ -702,6 +706,10 @@ export function GetClublogCtyInfo() {
   return window['go']['main']['App']['GetClublogCtyInfo']();
 }
 
+export function GetClublogMostWantedInfo() {
+  return window['go']['main']['App']['GetClublogMostWantedInfo']();
+}
+
 export function GetClusterAutoConnect() {
   return window['go']['main']['App']['GetClusterAutoConnect']();
 }
@@ -1666,6 +1674,10 @@ export function SetClublogCtyEnabled(arg1) {
   return window['go']['main']['App']['SetClublogCtyEnabled'](arg1);
 }
 
+export function SetClublogMostWantedEnabled(arg1) {
+  return window['go']['main']['App']['SetClublogMostWantedEnabled'](arg1);
+}
+
 export function SetClusterAutoConnect(arg1) {
   return window['go']['main']['App']['SetClusterAutoConnect'](arg1);
 }