chore(wailsv3): migrate Go backend from Wails v2 to v3

Minimal-structure migration to Wails v3.0.0-beta.20 (CLI-matching pin). Single App service preserved; no domain logic touched.

- main.go: wails.Run(options.App) -> application.New + RegisterService + Window.NewWithOptions. Window keeps title-with-version, 1024x768, RGBA background, Linux icon/translucency/GpuPolicyNever, ProgramName. SingleInstanceLock -> SingleInstanceOptions (same UniqueID); callback closes over the service variable set right after New.
- app.go: App holds *application.App instead of a context. startup(ctx) is gone; the version title moves into the window options via appTitle(). onSecondInstanceLaunch takes v3 SecondInstanceData (Args/WorkingDir) and uses Window.Current() Restore+Focus plus Event.Emit for launchArgs. ShowVersion uses Dialog.Info.
- AniList/MAL/Simkl *UserFunctions.go: runtime.BrowserOpenURL -> app.Browser.OpenURL (errors logged), runtime.MessageDialog -> app.Dialog.Info chains. OAuth callback servers, token flows, and key names unchanged.
- Secrets: 99designs/keyring replaced with zalando/go-keyring (what v3 itself depends on) under the same AniTrack service name, so existing stored tokens keep working. Per-file Set helpers kept; Open/Ready boilerplate deleted (zalando needs no handle).
- go.mod: v2 + 99designs dropped (stale v2 replace directive removed), v3 beta.20 + zalando v0.2.8 added.

SimklUserFunctions.go

@@ -11,41 +11,17 @@ import (
 	"net/http"
 	"sync"
 
-	"github.com/99designs/keyring"
-	"github.com/wailsapp/wails/v2/pkg/runtime"
+	"github.com/zalando/go-keyring"
 )
 
 var simklJwt SimklJWT
 
-var simklRing keyring.Keyring
-
-func init() {
-	var err error
-	simklRing, err = keyring.Open(keyring.Config{
-		ServiceName:                    "AniTrack",
-		KeychainName:                   "AniTrack",
-		KeychainSynchronizable:         false,
-		KeychainTrustApplication:       true,
-		KeychainAccessibleWhenUnlocked: true,
-	})
-	if err != nil {
-		log.Printf("simkl: secure storage unavailable: %s", err)
-	}
-}
-
-func simklRingReady() bool {
-	if simklRing == nil {
-		log.Println("simkl: secure storage unavailable")
-		return false
-	}
-	return true
-}
+// simklKeyringService is the OS keyring service name all AniTrack secrets
+// live under (same wallet the 99designs/keyring build used).
+const simklKeyringService = "AniTrack"
 
 func simklRingSet(key string, data []byte) error {
-	if !simklRingReady() {
-		return errors.New("simkl: secure storage unavailable")
-	}
-	if err := simklRing.Set(keyring.Item{Key: key, Data: data}); err != nil {
+	if err := keyring.Set(simklKeyringService, key, string(data)); err != nil {
 		log.Printf("simkl: save %s failed: %s", key, err)
 		return err
 	}
@@ -56,18 +32,15 @@ var simklCtxShutdown, simklCancel = context.WithCancel(context.Background())
 
 func (a *App) CheckIfSimklLoggedIn() bool {
 	if (SimklJWT{} == simklJwt) {
-		if !simklRingReady() {
-			return false
-		}
-		tokenType, tokenTypeErr := simklRing.Get("SimklTokenType")
-		accessToken, accessTokenErr := simklRing.Get("SimklAccessToken")
-		scope, scopeErr := simklRing.Get("SimklScope")
-		if (tokenTypeErr != nil || accessTokenErr != nil || scopeErr != nil) || len(accessToken.Data) == 0 {
+		tokenType, tokenTypeErr := keyring.Get(simklKeyringService, "SimklTokenType")
+		accessToken, accessTokenErr := keyring.Get(simklKeyringService, "SimklAccessToken")
+		scope, scopeErr := keyring.Get(simklKeyringService, "SimklScope")
+		if (tokenTypeErr != nil || accessTokenErr != nil || scopeErr != nil) || len(accessToken) == 0 {
 			return false
 		} else {
-			simklJwt.TokenType = string(tokenType.Data)
-			simklJwt.AccessToken = string(accessToken.Data)
-			simklJwt.Scope = string(scope.Data)
+			simklJwt.TokenType = tokenType
+			simklJwt.AccessToken = accessToken
+			simklJwt.Scope = scope
 			return true
 		}
 	} else {
@@ -77,25 +50,24 @@ func (a *App) CheckIfSimklLoggedIn() bool {
 
 func (a *App) SimklLogin() {
 	if !a.CheckIfSimklLoggedIn() {
-		if !simklRingReady() {
-			log.Println("simkl: cannot check login, secure storage unavailable")
-			return
-		}
-		tokenType, tokenTypeErr := simklRing.Get("SimklTokenType")
-		accessToken, accessTokenErr := simklRing.Get("SimklAccessToken")
-		scope, scopeErr := simklRing.Get("SimklScope")
-		if (tokenTypeErr != nil || accessTokenErr != nil || scopeErr != nil) || len(accessToken.Data) == 0 {
+		tokenType, tokenTypeErr := keyring.Get(simklKeyringService, "SimklTokenType")
+		accessToken, accessTokenErr := keyring.Get(simklKeyringService, "SimklAccessToken")
+		scope, scopeErr := keyring.Get(simklKeyringService, "SimklScope")
+		if (tokenTypeErr != nil || accessTokenErr != nil || scopeErr != nil) || len(accessToken) == 0 {
 			getSimklCodeUrl := "https://simkl.com/oauth/authorize?response_type=code&client_id=" + Environment.SIMKL_CLIENT_ID + "&redirect_uri=" + Environment.SIMKL_CALLBACK_URI
-			runtime.BrowserOpenURL(*wailsContext, getSimklCodeUrl)
+			if err := a.app.Browser.OpenURL(getSimklCodeUrl); err != nil {
+				log.Printf("simkl: failed to open browser: %s", err)
+				return
+			}
 
 			serverDone := &sync.WaitGroup{}
 			serverDone.Add(1)
 			a.handleSimklCallback(serverDone)
 			serverDone.Wait()
 		} else {
-			simklJwt.TokenType = string(tokenType.Data)
-			simklJwt.AccessToken = string(accessToken.Data)
-			simklJwt.Scope = string(scope.Data)
+			simklJwt.TokenType = tokenType
+			simklJwt.AccessToken = accessToken
+			simklJwt.Scope = scope
 		}
 	}
 }
@@ -117,17 +89,13 @@ func (a *App) handleSimklCallback(wg *sync.WaitGroup) {
 			_ = simklRingSet("SimklTokenType", []byte(simklJwt.TokenType))
 			_ = simklRingSet("SimklAccessToken", []byte(simklJwt.AccessToken))
 			_ = simklRingSet("SimklScope", []byte(simklJwt.Scope))
-			_, err := runtime.MessageDialog(*wailsContext, runtime.MessageDialogOptions{
-				Title:   "Simkl Authorization",
-				Message: "It is now safe to close your browser tab",
-			})
-			if err != nil {
-				log.Println(err)
-			}
+			a.app.Dialog.Info().
+				SetTitle("Simkl Authorization").
+				SetMessage("It is now safe to close your browser tab").
+				Show()
 			fmt.Println("Shutting down...")
 			simklCancel()
-			err = srv.Shutdown(context.Background())
-			if err != nil {
+			if err := srv.Shutdown(context.Background()); err != nil {
 				log.Println("server.Shutdown:", err)
 			}
 		} else {
@@ -243,13 +211,9 @@ func (a *App) GetSimklLoggedInUser() SimklUser {
 
 func (a *App) LogoutSimkl() string {
 	if (SimklJWT{} != simklJwt) {
-		if !simklRingReady() {
-			simklJwt = SimklJWT{}
-			return "Simkl Logged Out Successfully"
-		}
-		tokenTypeErr := simklRing.Remove("SimklTokenType")
-		accessTokenErr := simklRing.Remove("SimklAccessToken")
-		scopeErr := simklRing.Remove("SimklScope")
+		tokenTypeErr := keyring.Delete(simklKeyringService, "SimklTokenType")
+		accessTokenErr := keyring.Delete(simklKeyringService, "SimklAccessToken")
+		scopeErr := keyring.Delete(simklKeyringService, "SimklScope")
 
 		if tokenTypeErr != nil || accessTokenErr != nil || scopeErr != nil {
 			log.Printf("simkl: logout cleanup failed (type=%v access=%v scope=%v)", tokenTypeErr, accessTokenErr, scopeErr)