[kingchenc]

Scanning: NTFS MFT engine (Windows, administrator)

• New mft module: reads the volume's Master File Table straight from the
  volume (boot sector -> $MFT data runs -> 8 MB chunks read in parallel over
  four handles), applies update-sequence fixups and parses $STANDARD_INFORMATION,
  $FILE_NAME (8.3 aliases skipped, one entry per hard link), the unnamed $DATA
  stream (logical / allocated / compressed size) and reparse points. Metafiles,
  symbolic links and junctions are left out. All reads are bounds-checked.
• Without exclusions the tree is built straight from the records (no paths);
  with exclusions, and for the duplicate search, it emits the usual batches.
• Cloud placeholders and OneDrive-synced folders (from the OneDrive
  environment variables) are sized / listed through Windows, because only the
  cloud filter knows what is stored locally.
• Options::mft, CLI --mft; ScanTree::engine() and mft_fallback() say which
  engine ran and why the MFT was not used (no rights, not NTFS, ...).
• Measured (administrator, NVMe system drive): C:\Users\me 196 s -> 37 s with
  the walk vs the MFT, all of C: (4.8 M files, 4.9 M folders) in ~30 s; file
  counts and folder sizes match the walk. On a SATA SSD with millions of files
  the table is larger than the folders and the walk stays faster, which the
  settings text says.

Duplicates

• New dupes module: candidates of a repeated size are opened once, in
  parallel per file (not per size group), for their identity (hard links
  collapsed) and a BLAKE3 of the first and last 16 KB (files up to 32 KB are
  thereby hashed whole); only what still matches is hashed in full, big files
  on several threads via mmap. same-file dependency dropped.
• HashCache: path + size + modification time -> identity and hashes,
  zstd-compressed; find_duplicates_cached reuses it. CLI --cache FILE; the
  GUI keeps one in its data folder. A repeated search of a 461-group Steam
  library: 1.2 s -> 0.1 s, identical groups.
• Progress reports phases (list, compare ends, hash) with totals.
• Exclude globs are case-insensitive on Windows.

GUI

• Engine "Ultra (NTFS MFT)" with a restart-as-administrator button (and the
  note that Windows blocks drag & drop into an elevated window); "Admin" next
  to the version; the scan card shows "NTFS MFT" and a status line explains a
  fallback.
• Duplicate search skips program and game files unless included (the card
  offers a search that includes them); the progress card shows the three
  phases with counts, bytes and a real percentage.

Tests: 34 core (cache round trip and reuse, same ends / different middle,
in-order and out-of-order tree batches), 8 CLI, 23 UI helper tests.