fix: use unsigned char cast and sizeof in LogEscape escape sequence

[mangoostaa]

Found a small correctness issue in LogEscape():

• When char is signed (common on x86_64 Linux), negative byte values
  (e.g. 0xFF = -1) were being printed as ffffffff instead of ff.

• This fixes it by casting to unsigned char before %02x.

• Also changed the hardcoded 4 to sizeof(escape) so the code doesn't
  break silently if someone increases the buffer size later.

No performance impact, just safer and more portable.

[DrahtBot]

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