FFmpeg source availability for Karuiya 0.9.3.1

The source companion corresponding to this Karuiya binary package is available
at no charge from:

    https://downloads.karuiya.org/releases/0.9.3.1/Karuiya-0.9.3.1-open-source-sources.zip

Its SHA-256 is published at the same URL with the `.sha256` suffix. The matching
Karuiya 0.9.3.1 Windows binary and its SHA-256 are published in the same release
directory.

The source companion contains, at minimum:

- FFmpeg commit 1fdbca85aaea513c9cc6c14d347f76543346d3da source;
- BtbN/FFmpeg-Builds commit a99e8230eae00d1cee38f23076a7a1f55cd984e2
  scripts and patch set;
- Qt, PySide, Python, PyInstaller, and Qt-preview-FFmpeg source archives listed
  in `licenses/SOURCE_ARCHIVE_CHECKSUMS.txt`, including Qt Image Formats for the
  shipped WebP plugin;
- exact filenames, SHA-256 values, and official acquisition references for the
  pinned build-input wheels used to create the Windows package; and
- the configure output, binary version output, and component evidence supplied
  with this package.

The FFmpeg and BtbN archives are also included in
`licenses/FFmpeg-LGPL/corresponding-source` in the binary package.
`ENABLED_DEPENDENCY_SOURCE_REQUIREMENTS.md` records the additional third-party
source selected by the BtbN build scripts.

Source and release archives for this version are retained for at least three
years after the last distribution of the corresponding binary. For assistance
obtaining the source, contact `support@karuiya.org` or visit
https://karuiya.org/support/.

This record is not legal advice. The LGPL and each dependency's applicable
license text govern the corresponding component.
