feat(09-02): add shortcuts config package with default bindings and Wails persistence

- Create backend/shortcuts/config.go with DefaultBindings(), ApplyDefaults(), Validate()
- Wire Shortcuts field into main Config struct with TOML persistence
- Add GetShortcuts, SetShortcuts, SetShortcut, ResetShortcuts Wails binding methods
- Regenerate Wails TypeScript bindings for new config methods
- Fix wsl lint in library.go (blank line before logger call)

frontend/wailsjs/go/config/Config.d.ts

@@ -13,6 +13,8 @@ export function GetPinDefaultPlaylist():Promise<boolean>;
 
 export function GetScanConcurrency():Promise<string>;
 
+export function GetShortcuts():Promise<Record<string, string>>;
+
 export function GetThemeAccentColor():Promise<string>;
 
 export function GetThemeBackgroundShade():Promise<string>;
@@ -21,6 +23,8 @@ export function GetTrackListColumns():Promise<Array<tracklist.Column>>;
 
 export function Load():Promise<void>;
 
+export function ResetShortcuts():Promise<void>;
+
 export function Save():Promise<void>;
 
 export function SetContext(arg1:context.Context):Promise<void>;
@@ -35,6 +39,10 @@ export function SetPinDefaultPlaylist(arg1:boolean):Promise<void>;
 
 export function SetScanConcurrency(arg1:string):Promise<void>;
 
+export function SetShortcut(arg1:string,arg2:string):Promise<void>;
+
+export function SetShortcuts(arg1:Record<string, string>):Promise<void>;
+
 export function SetThemeAccentColor(arg1:string):Promise<void>;
 
 export function SetThemeBackgroundShade(arg1:string):Promise<void>;