fix(ci): avoid uv-managed python bootstrap on runners

scripts/ensure-ci-python.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+TARGET_VERSION="${1:-3.11}"
+IFS="." read -r PYTHON_MAJOR PYTHON_MINOR _ <<< "${TARGET_VERSION}"
+
+if [[ -n "${PYTHON_MINOR:-}" ]]; then
+  PYTHON_BIN="python${PYTHON_MAJOR}.${PYTHON_MINOR}"
+else
+  PYTHON_BIN="python${PYTHON_MAJOR}"
+fi
+
+if command -v "${PYTHON_BIN}" >/dev/null 2>&1; then
+  command -v "${PYTHON_BIN}"
+  exit 0
+fi
+
+export DEBIAN_FRONTEND=noninteractive
+
+apt-get update
+apt-get install -y software-properties-common
+add-apt-repository -y ppa:deadsnakes/ppa
+apt-get update
+apt-get install -y "${PYTHON_BIN}" "${PYTHON_BIN}-venv"
+
+command -v "${PYTHON_BIN}"