Closes#367 (reported by JohnBaumb).
The Docker entrypoint ran `pip install -U yt-dlp --quiet --no-cache-dir`
on every container start. Three problems with that:
- Non-deterministic startup: each restart could pick up a different
yt-dlp version, making "works on my machine" debugging harder.
- Network dependency at boot: PyPI being slow/unreachable gated the
app coming up.
- In-place upgrades inside running containers can race with active
yt-dlp invocations and aren't a great pattern.
Picked Option A from the issue: pin to an exact version in
requirements.txt (`yt-dlp==2026.3.17`) and remove the entrypoint
install entirely. yt-dlp comes baked into the image now via the
existing `pip install -r requirements.txt` in the Dockerfile.
Tradeoff: YouTube fixes ship via SoulSync releases now instead of
"next container restart". The pin is documented inline with how to
bump it.
Net change: -3 entrypoint lines, requirements.txt pin tightened,
WHATS_NEW '2.4.1' block opened (entries hidden until version bumps).
553 tests pass.
77a781caba
