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.d.ts

@@ -162,6 +162,8 @@ export function DownloadAndApplyUpdate(arg1:string):Promise<void>;
 
 export function DownloadClublogCty():Promise<main.ClublogCtyInfo>;
 
+export function DownloadClublogMostWanted():Promise<main.ClublogMostWantedInfo>;
+
 export function DownloadConfirmations(arg1:string,arg2:boolean,arg3:string):Promise<void>;
 
 export function DownloadLoTWUsers():Promise<number>;
@@ -374,6 +376,8 @@ export function GetChatHistory(arg1:number):Promise<Array<main.ChatMessage>>;
 
 export function GetClublogCtyInfo():Promise<main.ClublogCtyInfo>;
 
+export function GetClublogMostWantedInfo():Promise<main.ClublogMostWantedInfo>;
+
 export function GetClusterAutoConnect():Promise<boolean>;
 
 export function GetClusterStatus():Promise<Array<cluster.ServerStatus>>;
@@ -856,6 +860,8 @@ export function SetCATMode(arg1:string):Promise<void>;
 
 export function SetClublogCtyEnabled(arg1:boolean):Promise<void>;
 
+export function SetClublogMostWantedEnabled(arg1:boolean):Promise<void>;
+
 export function SetClusterAutoConnect(arg1:boolean):Promise<void>;
 
 export function SetCompactMode(arg1:boolean):Promise<void>;