refactor(router): check auto_scan_enabled before starting watch mode

- Add check for auto_scan_enabled setting in router before starting watch mode
- Update StartScanner handler to verify auto-scan is enabled
- Switch scanner to use watchModeCtx/watchModeCancel instead of ctx/cancel
- Update StartWatchModeForLibrary to use new MediaScanner signature

internal/router/router.go

@@ -13,6 +13,7 @@ import (
 	"context"
 	"log"
 	"net/http"
+	"strconv"
 	"strings"
 	"time"
 
@@ -238,6 +239,20 @@ func RegisterRoutes(cfg *Config) *handlers.Handler {
 	// Start watch mode for all libraries (after 2 second delay for DB)
 	go func() {
 		time.Sleep(2 * time.Second)
+		ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+
+		setting, err := cfg.Queries.GetSystemSetting(ctx, "auto_scan_enabled")
+		enabled := true // default
+		if err == nil && setting != "" {
+			enabled, _ = strconv.ParseBool(setting)
+		}
+
+		if !enabled {
+			log.Println("Auto-scan disabled in settings, skipping watch mode startup")
+			return
+		}
+
 		log.Println("Starting watch mode for all libraries...")
 		if err := scannerHandler.StartWatchModeForAllLibraries(context.Background()); err != nil {
 			log.Printf("Failed to start watch mode: %v", err)