[pset4] [recover] Add hashes for jpeg files without trailing zeros

[RCW679]

I wrote Recover from pset4 in such a way that it would actually parse the jpeg headers and look for EOI (FF D9), and stop there. This means that my implementation doesn't save the trailing zeros after EOI -- only to realize that the check50 checks failed with 'recovered image does not match', even though the actual content in the JPEG was the same. I then went to the checks and realized that it was using hashes of JPEG files with the trailing zeros. I then wrote a new Recover in such a way that it preserved the trailing zeros, and the checks passed.

The modifications in this PR add the hashes of the JPEG files without trailing zeros, while preserving the hashes of the JPEG files with the zeros.

[rongxin-liu]

Thanks for the thoughtful PR and explanation. Your approach is technically valid—stopping at FF D9 aligns with the JPEG spec. However, for this pset, we're leaning toward requiring students to recover files exactly as they appear on disk, including any trailing zeros. This somewhat reflects real-world data recovery and forensic principles, where byte-for-byte fidelity matters. Supporting multiple output variants would also increase complexity in check50. For those reasons, we’re going to stick with the current strict checks, but we appreciate your effort to improve the check50 checks.

cc @bxngyn @ivanharvard