fix cloud library scale and playback compatibility

Root cause: display-only cloud library filtering was reused by scan jobs, merged cloud mounts could be skipped, and OpenList listing relied on WebDAV/first-page behavior that could cap huge directories around 100 items. Cloud scans also let new items consume probe budget before existing rows with missing track/artwork metadata.\n\nChanges:\n- split display filtering from scannable cloud filtering so merged cloud mounts still scan\n- add OpenList API pagination with WebDAV fallback\n- prioritize existing cloud media missing metadata before new imports\n- restrict automatic cloud sync to one successful 19:00-21:00 daily window and keep manual scan immediate\n- disable startup cloud full-scan by default, with an explicit opt-in setting\n- improve Emby/cloud playback compatibility and cache/search/test coverage from the continued work

internal/service/boot_cloud.go

@@ -7,21 +7,32 @@ import (
 	"go.uber.org/zap"
 
 	"github.com/ShukeBta/MediaStationGo/internal/model"
+	"github.com/ShukeBta/MediaStationGo/internal/repository"
 )
 
-// BootCloudLibraries 在系统启动后自动扫描所有云盘媒体库，使媒体对所有用户立即可见。
-// 避免每个用户首次访问时都触发扫描。
+// BootCloudLibraries optionally scans cloud libraries after startup. It is
+// disabled by default for huge cloud mounts; normal automatic refresh is handled
+// by the nightly cloud_sync scheduler window, and operators can still scan
+// manually at any time.
 func (c *Container) BootCloudLibraries(ctx context.Context) {
 	if c == nil || c.Repo == nil || c.Scan == nil {
 		return
 	}
+	if !bootCloudLibraryScanEnabled(ctx, c.Repo) {
+		c.Log.Info("boot: cloud library scans disabled; use manual scan or nightly cloud sync")
+		return
+	}
 	libs, err := c.Repo.Library.List(ctx)
 	if err != nil {
 		c.Log.Warn("boot cloud libraries: list failed", zap.Error(err))
 		return
 	}
+	libs = FilterScannableCloudLibraries(ctx, c.Repo, libs)
 	cloudLibs := make([]model.Library, 0)
 	for _, lib := range libs {
+		if !lib.Enabled {
+			continue
+		}
 		if _, ok := ParseCloudLibraryMount(lib.Path); ok {
 			cloudLibs = append(cloudLibs, lib)
 		}
@@ -32,19 +43,32 @@ func (c *Container) BootCloudLibraries(ctx context.Context) {
 	c.Log.Info("boot: scheduling cloud library scans", zap.Int("count", len(cloudLibs)))
 	// 延迟3秒后启动，避免和系统初始化任务冲突
 	time.AfterFunc(3*time.Second, func() {
-		for _, lib := range cloudLibs {
-			libID := lib.ID
-			libName := lib.Name
-			go func() {
-				scanCtx, cancel := context.WithTimeout(context.Background(), 2*time.Hour)
-				defer cancel()
-				c.Log.Info("boot: scanning cloud library", zap.String("id", libID), zap.String("name", libName))
-				if _, err := c.Scan.ScanLibraryWithoutAutoScrape(scanCtx, libID); err != nil {
-					c.Log.Warn("boot: cloud library scan failed", zap.String("id", libID), zap.String("name", libName), zap.Error(err))
-				} else {
-					c.Log.Info("boot: cloud library scan completed", zap.String("id", libID), zap.String("name", libName))
-				}
-			}()
-		}
+		go c.runBootCloudLibraryScanQueue(cloudLibs)
 	})
 }
+
+func (c *Container) runBootCloudLibraryScanQueue(cloudLibs []model.Library) {
+	for _, lib := range cloudLibs {
+		libID := lib.ID
+		libName := lib.Name
+		scanCtx, cancel := context.WithTimeout(context.Background(), 2*time.Hour)
+		c.Log.Info("boot: scanning cloud library", zap.String("id", libID), zap.String("name", libName))
+		if _, err := c.Scan.ScanLibraryWithoutAutoScrape(scanCtx, libID); err != nil {
+			c.Log.Warn("boot: cloud library scan failed", zap.String("id", libID), zap.String("name", libName), zap.Error(err))
+		} else {
+			c.Log.Info("boot: cloud library scan completed", zap.String("id", libID), zap.String("name", libName))
+		}
+		cancel()
+	}
+}
+
+func bootCloudLibraryScanEnabled(ctx context.Context, repo *repository.Container) bool {
+	if repo == nil || repo.Setting == nil {
+		return false
+	}
+	value, err := repo.Setting.Get(ctx, "cloud.boot_scan_enabled")
+	if err != nil {
+		return false
+	}
+	return parseBoolSetting(value, false)
+}