v0.12.3 — Security & correctness bug fixes (33 bugs)

CRITICAL: 10 data race and security fixes — backup.go mutex coverage
(C1-C4), IsSystemDisk 12-bit major/minor (C5), /dev/ path validation
(C6), extractName traversal (C7), TargetPath/DestinationPath against
registered paths (C8-C9), ParseComposeHDDMounts Clean-before-prefix (C10).

HIGH: 17 logic/resource fixes — ValidateDump bufio.Scanner (H1), single
appDirSize() with 30s timeout (H2/H3), snapshot ID regex (H4), cross-drive
restic prune (H5), temp file order (H6), dirSizeBytes errors (H7), atomic
fstab (H8), IsDeviceMounted suffix check (H9), eMMC partition mapping (H10),
bytesCopied mutex (H11), separator-aware migrate prefix (H13), DeleteStack
error on compose-down (H14), docker 60s timeout (H16), NotificationPrefs
deep-copy (H17), wipefs warning (H18), fstab rollback on mount fail (H19).

MEDIUM: 7 code quality fixes — formatBytes dedup (M1), .tmp filter order
(M2), sizeBytes string type (M3), elapsed in message (M6), LoadLocation
fallback (M7), pathCovers separator (M10), cancelEditLabel textContent (M11).

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

controller/internal/backup/restic.go

@@ -173,7 +173,7 @@ func (r *ResticManager) Snapshot(paths []string, tags []string) (*SnapshotResult
 			result.SnapshotID = msg.SnapshotID
 			result.FilesNew = msg.FilesNew
 			result.FilesChanged = msg.FilesChanged
-			result.DataAdded = formatBytes(msg.DataAdded)
+			result.DataAdded = humanizeBytes(msg.DataAdded)
 		}
 	}
 
@@ -282,7 +282,7 @@ func (r *ResticManager) Stats() (*RepoStats, error) {
 			TotalSize uint64 `json:"total_size"`
 		}
 		if json.Unmarshal(out, &raw) == nil {
-			stats.TotalSize = formatBytes(int64(raw.TotalSize))
+			stats.TotalSize = humanizeBytes(int64(raw.TotalSize))
 		}
 	}