chore: report symphonia's 1 KB hvcC cap upstream #75

symphonia-format-isomp4 hard-caps the hvcC HEVCDecoderConfigurationRecord at 1 KB:

const MAX_HVCC_ATOM_SIZE: u64 = 1 * 1024;
// "This record forms the defacto codec extra data. It should not exceed 1 kB."
Some(_) => return decode_error("isomp4 (hvcC): atom size is greater than 1 kb"),

That comment is wrong. Real HEVC records routinely exceed 1 KB — a plain ffmpeg -c:v libx265 clip produced a 2440-byte hvcC here, and camera encoders are larger. avcC carries the same cap (MAX_AVCC_ATOM_SIZE), which is more generous in practice for AVC but is the same class of bug.

The error aborts IsoMp4Reader::try_new, so every affected file fails to open entirely rather than degrading.

rawshift moved its MP4 backend to mp4-atom for this and four related reasons (see #68), so this is not blocking us — filing it because it silently breaks HEVC in MP4/MOV for anyone else using that demuxer, and the fix is raising or removing one constant.

Worth reporting upstream at https://github.com/pdeljanov/Symphonia. No existing issue was found for it.