fix: USB badge detection for bind-mounted drives + graceful Tier2 backup on disconnected destinations

- IsUSBDevice/diskModel: strip findmnt bind-mount suffix [/subdir] before
  parsing device path (fixes USB badge not showing for attach-wizard drives)
- crossdrive.go: skip disconnected src/dest drives with WARN log instead of
  returning error (prevents noisy error status in settings.json)
- handlers.go: detect Tier2 destination disconnection, set yellow status dot
  instead of red, skip ValidateDestination for disconnected paths
- backups.html: new template branch showing "Cél meghajtó leválasztva" badge
  with grayed-out info and hidden "Futtatás most" button

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

controller/internal/web/handlers.go

@@ -785,6 +785,8 @@ type AppBackupRow struct {
 
 	// Drive disconnected — app's home drive is currently disconnected
 	DriveDisconnected bool
+	// Tier2 destination drive is currently disconnected (backup paused, not failed)
+	Tier2DestDisconnected bool
 
 	// Warnings accumulated for this app
 	Warnings []string
@@ -926,8 +928,22 @@ func (s *Server) buildAppBackupRows(
 				// Tier2 configured but never run — stay yellow
 			}
 
-			// Destination health check — can downgrade green to yellow/red
-			if cfg.DestinationPath != "" && s.crossDriveRunner != nil {
+			// Check if Tier2 destination drive is disconnected
+			if cfg.DestinationPath != "" {
+				for dp := range disconnectedPaths {
+					if cfg.DestinationPath == dp || strings.HasPrefix(cfg.DestinationPath, dp+"/") {
+						row.Tier2DestDisconnected = true
+						break
+					}
+				}
+			}
+
+			if row.Tier2DestDisconnected {
+				// Disconnected destination — treat as paused, not failed
+				row.Status = "yellow"
+				row.StatusText = "2. mentés szünetel — cél meghajtó leválasztva"
+			} else if cfg.DestinationPath != "" && s.crossDriveRunner != nil {
+				// Destination health check — can downgrade green to yellow/red
 				if err := s.crossDriveRunner.ValidateDestination(cfg.DestinationPath); err != nil {
 					if strings.Contains(err.Error(), "does not exist") || strings.Contains(err.Error(), "not writable") {
 						row.Status = "red"