oss policy review check (#23)

This pull request introduces a CI workflow to enforce license headers
and adds the required Elastic License 2.0 header to several Python
package `__init__.py` files. The main goal is to ensure all source files
comply with licensing requirements.

**CI/CD Improvements:**

* Added a `license-headers` job to the GitHub Actions workflow
(`.github/workflows/ci.yml`) that checks all `.py` files (excluding
`.venv`, `dist`, and `build` directories) for the Elastic License 2.0
header and fails the build if any files are missing it.

**License Compliance:**

* Added the Elastic License 2.0 header to the `__init__.py` files in the
following directories: `examples/chatbot_rag_app/datasets`,
`examples/chatbot_rag_app/evaluators`, `examples/chatbot_rag_app/tasks`,
`examples/claude_code_eval`, `examples/claude_code_eval/datasets`,
`examples/claude_code_eval/evaluators`, and
`examples/claude_code_eval/tasks`.## Summary

---------

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: masci

.pre-commit-config.yaml

@@ -5,3 +5,12 @@ repos:
       - id: ruff-check
         args: [--fix]
       - id: ruff-format
+
+  - repo: local
+    hooks:
+      - id: license-headers
+        name: Check Elastic License 2.0 headers
+        entry: bash -c 'missing=$(grep -L "Licensed under the Elastic License 2.0" "$@"); if [ -n "$missing" ]; then echo "Files missing Elastic License 2.0 header:"; echo "$missing"; exit 1; fi' --
+        language: system
+        types: [python]
+        exclude: ^(\.venv|dist|build)/

examples/chatbot_rag_app/datasets/__init__.py

@@ -1 +1,3 @@
-
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/chatbot_rag_app/evaluators/__init__.py

@@ -1 +1,3 @@
-
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/chatbot_rag_app/tasks/__init__.py

@@ -1 +1,3 @@
-
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/claude_code_eval/__init__.py

@@ -0,0 +1,3 @@
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/claude_code_eval/datasets/__init__.py

@@ -0,0 +1,3 @@
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/claude_code_eval/evaluators/__init__.py

@@ -0,0 +1,3 @@
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.

examples/claude_code_eval/tasks/__init__.py

@@ -0,0 +1,3 @@
+# Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+# or more contributor license agreements. Licensed under the Elastic License 2.0;
+# you may not use this file except in compliance with the Elastic License 2.0.