feat: Tier2 backup pauses when destination drive is inactive (Inaktív)

Deactivated drives (Schedulable=false) now treated like disconnected for
Tier2 backups. New IsStoragePathSchedulable() checks active+connected+not
decommissioned. UI shows yellow "Cél meghajtó inaktív" badge, scheduler
skips silently with WARN log.

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

controller/internal/settings/settings.go

@@ -707,6 +707,20 @@ func (s *Settings) IsStoragePathKnown(path string) bool {
 	return false
 }
 
+// IsStoragePathSchedulable returns whether a path belongs to a registered,
+// schedulable (active) storage path. Returns false if the path is unknown,
+// disconnected, decommissioned, or inactive.
+func (s *Settings) IsStoragePathSchedulable(path string) bool {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	for _, sp := range s.StoragePaths {
+		if path == sp.Path || strings.HasPrefix(path, sp.Path+"/") {
+			return sp.Schedulable && !sp.Disconnected && !sp.Decommissioned
+		}
+	}
+	return false
+}
+
 // GetStoppedStacks returns the list of stacks that were auto-stopped for a storage path.
 func (s *Settings) GetStoppedStacks(path string) []string {
 	s.mu.RLock()