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/web/templates/backups.html

@@ -306,6 +306,17 @@
                         <div class="layer-actions">
                             <a href="/stacks/{{.StackName}}/deploy" class="btn btn-xs btn-outline">Beállítás</a>
                         </div>
+                    {{else if and .Tier2Configured .Tier2DestInactive}}
+                        <span class="layer-method" style="opacity:.6">rsync</span>
+                        <span class="layer-dest" style="opacity:.6">→ {{.Tier2Dest}}</span>
+                        <span class="badge badge-warn" style="font-size:.7rem">Cél meghajtó inaktív</span>
+                        {{if .Tier2LastRun}}
+                        <span class="layer-last" style="opacity:.6">Utolsó: {{.Tier2LastRun}}</span>
+                        {{end}}
+                        <span class="tier-contents" style="opacity:.6">{{.BackupContents}}</span>
+                        <div class="layer-actions">
+                            <a href="/stacks/{{.StackName}}/deploy" class="btn btn-xs btn-outline">Beállítás</a>
+                        </div>
                     {{else if .Tier2Configured}}
                         <span class="layer-method">rsync</span>
                         <span class="layer-dest">→ {{.Tier2Dest}}</span>