fix pull step: add python path and use --python 3.14 for uv sync
uv installs python to ~/.local/bin (not on PATH in container), and
uv sync defaults to system python prefix /usr/local which isn't a venv.
--python 3.14 creates a proper .venv with the managed interpreter.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>