The CLI paints progress as carriage-return frames ("\r path [###] 42%", no
newline until 100%). Worker.run read the child line-by-line, so it emitted
NOTHING for the whole job and the GUI looked frozen on any file bigger than one
block — reported as 'I can't compress, the app stucks'. The worker now reads
with read1() and splits on both \n and \r, parsing the percentage out of the
progress frames and driving the QProgressBar (indeterminate until the first %).
Also run the child with stdin=/dev/null (a prompt on inherited stdin would block
forever) and merge stderr into stdout so a filling second pipe can't deadlock.
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