v0.12.2: restore section simplification — snapshot filtering, auto-stop/restart, UI cleanup

- StackDataProvider interface extended with StopStack/StartStack
- backup.Manager.GetStackHDDMounts() delegates to stackProvider
- RestoreApp() auto-stops app before restic restore, restarts after (even on failure)
- stackAdapter in main.go wires StopStack/StartStack through to stacks.Manager
- GET /api/backup/snapshots?stack={name} filters snapshots by app HDD paths via filterSnapshotsByPaths()
- Restore section simplified: no path list, per-app filtered snapshots, human-friendly timestamp format, single calm warning, empty-result inline message

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

controller/internal/backup/restore.go

@@ -51,12 +51,26 @@ func (m *Manager) RestoreApp(stackName, snapshotID string) error {
 
 	m.logger.Printf("[WARN] RESTORE starting: stack=%s, snapshot=%s, paths=%v", stackName, snapshotID, hddMounts)
 
+	// Stop the app before restore to avoid data corruption
+	if err := m.stackProvider.StopStack(stackName); err != nil {
+		m.logger.Printf("[WARN] RESTORE could not stop %s before restore: %v (proceeding anyway)", stackName, err)
+	}
+
 	// Execute restore
 	if err := m.restic.RestoreAppData(snapshotID, hddMounts); err != nil {
 		m.logger.Printf("[ERROR] RESTORE failed for %s: %v", stackName, err)
+		// Try to restart the app even on failure
+		if startErr := m.stackProvider.StartStack(stackName); startErr != nil {
+			m.logger.Printf("[WARN] RESTORE could not restart %s after failed restore: %v", stackName, startErr)
+		}
 		return err
 	}
 
+	// Restart the app after successful restore
+	if err := m.stackProvider.StartStack(stackName); err != nil {
+		m.logger.Printf("[WARN] RESTORE could not restart %s after restore: %v", stackName, err)
+	}
+
 	m.logger.Printf("[INFO] RESTORE completed: stack=%s, snapshot=%s", stackName, snapshotID)
 	return nil
 }