Wolfi now resolves unpinned `python3` to 3.14. uvloop 0.21.0 has no 3.14
wheel, so uv builds it from sdist and libuv's configure bootstrap fails,
killing every Docker image job in `uv sync`. This is the same failure that
took down the 1.99.0 release pipeline.
Cherry-picks #38917 (merge f814945d4c) onto stable/1.97.x: pins
python-3.13 / python-3.13-dev in every apk layer, passes --python
python3.13 to each uv sync, and sets UV_PYTHON_DOWNLOADS=0 so a missing
interpreter fails loudly instead of silently downloading one.
The wolfi-base digest hunks conflicted -- stable/1.97.x sits at 42df77a9
while #38917 moved a31344ab -> e624c5d5. Resolved to e624c5d5, the base
the 1.99.0 images build and ship on today.
migrations/Dockerfile is deliberately untouched; that image is covered by
#38973, which is not part of this pick.
(cherry picked from commit f814945d4c)