ci: standardize Python venv setup across all workflows using setup-python-venv.sh script

Replaced manual venv creation and pip install commands with calls to scripts/ci/setup-python-venv.sh across all CI workflows. The script provides consistent venv setup with configurable options for requirements installation, copy mode, and extra packages.

- Changed from manual `python3 -m venv` + `pip install` to setup-python-venv.sh in all workflows
- Added --skip-requirements flag where workflows don't need requirements

scripts/ci/setup-python-venv.sh

@@ -0,0 +1,147 @@
+#!/bin/bash
+set -euo pipefail
+
+REPO_DIR="$(pwd)"
+VENV_DIR=""
+REQUIREMENTS_FILE=""
+SKIP_REQUIREMENTS="false"
+MODE="symlink"
+EXTRA_PACKAGES=""
+CACHE_ROOT="/var/cache/aitbc/python-venvs"
+PIP_CACHE_ROOT="/var/cache/aitbc/pip"
+PYTHON_BIN="${PYTHON_BIN:-python3}"
+
+while [[ $# -gt 0 ]]; do
+    case "$1" in
+        --repo-dir)
+            REPO_DIR="$2"
+            shift 2
+            ;;
+        --venv-dir)
+            VENV_DIR="$2"
+            shift 2
+            ;;
+        --requirements-file)
+            REQUIREMENTS_FILE="$2"
+            shift 2
+            ;;
+        --skip-requirements)
+            SKIP_REQUIREMENTS="true"
+            shift
+            ;;
+        --mode)
+            MODE="$2"
+            shift 2
+            ;;
+        --extra-packages)
+            EXTRA_PACKAGES="$2"
+            shift 2
+            ;;
+        --cache-root)
+            CACHE_ROOT="$2"
+            shift 2
+            ;;
+        --python-bin)
+            PYTHON_BIN="$2"
+            shift 2
+            ;;
+        *)
+            echo "Unknown argument: $1" >&2
+            exit 1
+            ;;
+    esac
+done
+
+VENV_DIR="${VENV_DIR:-$REPO_DIR/venv}"
+REQUIREMENTS_FILE="${REQUIREMENTS_FILE:-$REPO_DIR/requirements.txt}"
+
+if [[ "$SKIP_REQUIREMENTS" == "true" ]]; then
+    REQUIREMENTS_FILE=""
+fi
+
+if [[ "$MODE" != "symlink" && "$MODE" != "copy" ]]; then
+    echo "Invalid mode: $MODE" >&2
+    exit 1
+fi
+
+if [[ ! -d "$REPO_DIR" ]]; then
+    echo "Repository directory not found: $REPO_DIR" >&2
+    exit 1
+fi
+
+if ! command -v "$PYTHON_BIN" >/dev/null 2>&1; then
+    echo "Python binary not found: $PYTHON_BIN" >&2
+    exit 1
+fi
+
+export PIP_DISABLE_PIP_VERSION_CHECK=1
+export PIP_NO_INPUT=1
+export PIP_PROGRESS_BAR=off
+export PIP_CACHE_DIR="$PIP_CACHE_ROOT"
+
+mkdir -p "$CACHE_ROOT" "$PIP_CACHE_ROOT"
+
+PYTHON_VERSION="$($PYTHON_BIN -c 'import sys; print(".".join(map(str, sys.version_info[:3])))')"
+if [[ -n "$REQUIREMENTS_FILE" && -f "$REQUIREMENTS_FILE" ]]; then
+    REQUIREMENTS_HASH="$(sha256sum "$REQUIREMENTS_FILE" | awk '{print $1}' | cut -c1-16)"
+else
+    REQUIREMENTS_HASH="no-req"
+fi
+EXTRA_HASH="$(printf '%s' "$EXTRA_PACKAGES" | sha256sum | awk '{print $1}' | cut -c1-16)"
+CACHE_KEY="py${PYTHON_VERSION}-req${REQUIREMENTS_HASH}-extra${EXTRA_HASH}"
+CACHE_VENV_DIR="$CACHE_ROOT/$CACHE_KEY"
+LOCK_FILE="$CACHE_ROOT/$CACHE_KEY.lock"
+
+build_cached_environment() {
+    local temp_dir
+    temp_dir="${CACHE_VENV_DIR}.tmp.$$"
+
+    rm -rf "$temp_dir"
+    "$PYTHON_BIN" -m venv "$temp_dir"
+    source "$temp_dir/bin/activate"
+
+    python -m pip install -q --upgrade pip setuptools wheel
+
+    if [[ -n "$REQUIREMENTS_FILE" && -f "$REQUIREMENTS_FILE" ]]; then
+        python -m pip install -q -r "$REQUIREMENTS_FILE"
+    fi
+
+    if [[ -n "$EXTRA_PACKAGES" ]]; then
+        read -r -a extra_array <<< "$EXTRA_PACKAGES"
+        python -m pip install -q "${extra_array[@]}"
+    fi
+
+    deactivate || true
+    mv "$temp_dir" "$CACHE_VENV_DIR"
+}
+
+if command -v flock >/dev/null 2>&1; then
+    exec 9>"$LOCK_FILE"
+    flock 9
+fi
+
+if [[ -x "$CACHE_VENV_DIR/bin/python" ]]; then
+    echo "✅ Reusing cached Python environment: $CACHE_KEY"
+else
+    echo "📦 Building cached Python environment: $CACHE_KEY"
+    build_cached_environment
+fi
+
+rm -rf "$VENV_DIR"
+
+case "$MODE" in
+    symlink)
+        ln -s "$CACHE_VENV_DIR" "$VENV_DIR"
+        ;;
+    copy)
+        mkdir -p "$VENV_DIR"
+        if command -v rsync >/dev/null 2>&1; then
+            rsync -a --delete "$CACHE_VENV_DIR/" "$VENV_DIR/"
+        else
+            cp -a "$CACHE_VENV_DIR/." "$VENV_DIR/"
+        fi
+        ;;
+esac
+
+source "$VENV_DIR/bin/activate"
+echo "✅ Python environment ready from cache: $CACHE_KEY"