feat: show 'Internal' version in debug builds, optimize download timeouts, and fix navigation safety

- Add displayVersion getter using kDebugMode: debug shows 'Internal', release shows actual version
- Defer Spotify URL resolution in Deezer downloader until fallback is actually needed
- Unify download timeouts to 24h constant (connection-level timeouts still protect hung connections)
- Fix context shadowing in track metadata options menu and delete dialog
- Use addPostFrameCallback + mounted guards for safer sheet/dialog navigation

go_backend/deezer_download.go

@@ -394,11 +394,6 @@ func downloadFromDeezer(req DownloadRequest) (DeezerDownloadResult, error) {
 		}
 	}
 
-	spotifyURL, err := resolveSpotifyURLForYoinkify(req)
-	if err != nil {
-		return DeezerDownloadResult{}, err
-	}
-
 	filename := buildFilenameFromTemplate(req.FilenameFormat, map[string]interface{}{
 		"title":  req.TrackName,
 		"artist": req.ArtistName,
@@ -461,6 +456,17 @@ func downloadFromDeezer(req DownloadRequest) (DeezerDownloadResult, error) {
 	}
 
 	if downloadErr != nil || deezerURLErr != nil {
+		spotifyURL, err := resolveSpotifyURLForYoinkify(req)
+		if err != nil {
+			if deezerURLErr != nil {
+				return DeezerDownloadResult{}, fmt.Errorf(
+					"deezer download failed: direct Deezer resolution error: %v; Yoinkify fallback error: %w",
+					deezerURLErr,
+					err,
+				)
+			}
+			return DeezerDownloadResult{}, err
+		}
 		downloadErr = deezerClient.DownloadFromYoinkify(spotifyURL, outputPath, req.OutputFD, req.ItemID)
 		if downloadErr != nil {
 			if errors.Is(downloadErr, ErrDownloadCancelled) {

go_backend/extension_providers.go

@@ -484,7 +484,7 @@ func (p *ExtensionProviderWrapper) GetDownloadURL(trackID, quality string) (*Ext
 	return &urlResult, nil
 }
 
-const ExtDownloadTimeout = 5 * time.Minute
+const ExtDownloadTimeout = DownloadTimeout
 
 func (p *ExtensionProviderWrapper) Download(trackID, quality, outputPath string, onProgress func(percent int)) (*ExtDownloadResult, error) {
 	if !p.extension.Manifest.IsDownloadProvider() {

go_backend/httputil.go

@@ -31,7 +31,7 @@ func getRandomUserAgent() string {
 
 const (
 	DefaultTimeout    = 60 * time.Second
-	DownloadTimeout   = 120 * time.Second
+	DownloadTimeout   = 24 * time.Hour
 	SongLinkTimeout   = 30 * time.Second
 	DefaultMaxRetries = 3
 	DefaultRetryDelay = 1 * time.Second

go_backend/tidal.go

@@ -583,7 +583,7 @@ func (t *TidalDownloader) downloadFromManifest(ctx context.Context, manifestB64,
 	GoLog("[Tidal] Manifest parsed - directURL: %v, initURL: %v, mediaURLs count: %d\n",
 		directURL != "", initURL != "", len(mediaURLs))
 
-	client := NewHTTPClientWithTimeout(120 * time.Second)
+	client := NewHTTPClientWithTimeout(DownloadTimeout)
 
 	if directURL != "" {
 		GoLog("[Tidal] BTS format - downloading from direct URL: %s...\n", directURL[:min(80, len(directURL))])

go_backend/youtube.go

@@ -11,7 +11,6 @@ import (
 	"strconv"
 	"strings"
 	"sync"
-	"time"
 )
 
 type YouTubeDownloader struct {
@@ -82,7 +81,7 @@ type YouTubeDownloadResult struct {
 func NewYouTubeDownloader() *YouTubeDownloader {
 	youtubeDownloaderOnce.Do(func() {
 		globalYouTubeDownloader = &YouTubeDownloader{
-			client: NewHTTPClientWithTimeout(120 * time.Second),
+			client: NewHTTPClientWithTimeout(DownloadTimeout),
 			apiURL: "https://api.qwkuns.me",
 		}
 	})