Add FLAC audio quality analysis and spectrum visualization (#110)

Introduces backend support for analyzing FLAC audio files, including technical metrics and frequency spectrum extraction. Adds frontend components and hooks for file selection, analysis, and visualization, integrating a new Audio Quality Analyzer dialog into the UI. Updates types and dependencies to support audio analysis features.

backend/folder.go

@@ -48,3 +48,31 @@ func SelectFolderDialog(ctx context.Context, defaultPath string) (string, error)
 
 	return selectedPath, nil
 }
+
+func SelectFileDialog(ctx context.Context) (string, error) {
+	options := wailsRuntime.OpenDialogOptions{
+		Title: "Select FLAC File for Analysis",
+		Filters: []wailsRuntime.FileFilter{
+			{
+				DisplayName: "FLAC Audio Files (*.flac)",
+				Pattern:     "*.flac",
+			},
+			{
+				DisplayName: "All Files (*.*)",
+				Pattern:     "*.*",
+			},
+		},
+	}
+
+	selectedFile, err := wailsRuntime.OpenFileDialog(ctx, options)
+	if err != nil {
+		return "", err
+	}
+
+	// If user cancelled, selectedFile will be empty
+	if selectedFile == "" {
+		return "", nil
+	}
+
+	return selectedFile, nil
+}