ci: add python package build test (#2457)

# What does this PR do?

We now test a package build on every PRs.

Closes: https://github.com/meta-llama/llama-stack/issues/2406

Signed-off-by: Sébastien Han <seb@redhat.com>

scripts/check-init-py.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+#
+# Check for missing __init__.py files in Python packages
+# This script finds directories that contain Python files but are missing __init__.py
+
+set -euo pipefail
+
+# Use mapfile to get a faster way to iterate over directories
+if (( BASH_VERSINFO[0] < 4 )); then
+    echo "This script requires Bash 4.0 or higher for mapfile support."
+    exit 1
+fi
+
+PACKAGE_DIR="${1:-llama_stack}"
+
+if [ ! -d "$PACKAGE_DIR" ]; then
+    echo "ERROR: Package directory '$PACKAGE_DIR' does not exist"
+    exit 1
+fi
+
+# Get all directories with Python files (excluding __init__.py)
+mapfile -t py_dirs < <(
+    find "$PACKAGE_DIR" \
+        -type f \
+        -name "*.py" ! -name "__init__.py" \
+        ! -path "*/.venv/*" \
+        -exec dirname {} \; | sort -u
+)
+
+missing_init_files=0
+
+for dir in "${py_dirs[@]}"; do
+    if [ ! -f "$dir/__init__.py" ]; then
+        echo "ERROR: Missing __init__.py in directory: $dir"
+        echo "This directory contains Python files but no __init__.py, which may cause packaging issues."
+        missing_init_files=1
+    fi
+done
+
+exit $missing_init_files