DJ USB Tkit 0.1.3

• Fix USB export becoming permanently blocked with a "PDB export blocked"
  error once a USB's playlist list had grown large enough to need extra
  internal storage space for a new playlist — affected any USB that had
  accumulated enough playlists over time, making it impossible to export any
  further new playlist to it.
• Fix USB diagnostics permanently reporting one unfixable "history page
  shape" issue on USBs with a single-entry history-menu page; repair now
  correctly recognizes it as already valid.
• Internal: clean up clippy lint warnings and apply cargo fmt across the
  backend and desktop crates (no functional changes).
• Detect WAV files using the WAVE_FORMAT_EXTENSIBLE header, which some
  Pioneer CDJs reject even when the underlying audio is otherwise within
  spec. Flagged during library scan with a format-badge tooltip; when the
  extensible header wraps plain PCM/IEEE-float data, export automatically
  rewrites it to a standard header (lossless, no re-encoding) so the file
  plays on CDJ hardware.