Reuses libheif's own LGPL/MIT-licensed with-alpha-512x512.heic sample
under both a .heic and .heif filename, verified to decode correctly
via heic-convert (the library the image format work will use). No
suitably-licensed HEVC/mif1-branded .heif-distinct sample exists that
is compatible with the pinned libheif-js version, and file-type detects
both extensions identically regardless of container brand, so the
duplicate content is sufficient to exercise the heif source-format
code path.
Regenerates the sample.png test fixture via sharp itself: the
hand-encoded base64 PNG from the plan had valid magic bytes (enough to
fool file-type's signature check) but was malformed past the header,
which libpng rejected as soon as sharp actually tried to decode it.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
anthony
