feat: add SyncAll periodic sync pipeline and wire Navidrome client into App

cmd/naviwatcher/main.go

@@ -12,6 +12,7 @@ import (
 	"naviwatcher/internal/config"
 	"naviwatcher/internal/database"
 	"naviwatcher/internal/musicbrainz"
+	"naviwatcher/internal/navidrome"
 	"naviwatcher/internal/scanner"
 )
 
@@ -20,8 +21,14 @@ type App struct {
 	cfg      *config.Config
 	db       *database.DB
 	mbClient *musicbrainz.MusicBrainzClient
+	ndClient *navidrome.NavidromeClient
 }
 
+// navidromeClientFactory constructs the Navidrome client. It is a package-level
+// variable (not a direct call to navidrome.NewClient) so tests can inject a stub
+// without requiring a live Navidrome server for authentication.
+var navidromeClientFactory = navidrome.NewClient
+
 const defaultConfigPath = "config.yaml"
 
 func main() {
@@ -76,10 +83,17 @@ func NewApp(ctx context.Context, cfg *config.Config, dbPath string) (*App, error
 
 	log.Printf("MusicBrainz client initialized (user-agent: %s)", cfg.MusicBrainz.UserAgent)
 
+	// Initialize Navidrome client (authenticates immediately; error if auth fails).
+	ndClient, err := navidromeClientFactory(cfg.Navidrome)
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize navidrome client: %w", err)
+	}
+
 	return &App{
 		cfg:      cfg,
 		db:       db,
 		mbClient: mbClient,
+		ndClient: ndClient,
 	}, nil
 }
 
@@ -88,6 +102,10 @@ func (a *App) Close() {
 	if a.mbClient != nil {
 		a.mbClient.Close()
 	}
+	if a.ndClient != nil {
+		// NavidromeClient holds a stateless subsonic client; nothing to close
+		// beyond releasing idle connections tracked by the MusicBrainz client.
+	}
 	if a.db != nil {
 		if err := a.db.Close(); err != nil {
 			log.Printf("Error closing database: %v", err)