Fix conftest collision between codeflash-api and github-app test suites

Both packages had tests/__init__.py, creating competing `tests`
packages under --import-mode=importlib. Remove both __init__.py files
and change github-app imports from `from tests.helpers` to
`from helpers` via sys.path insertion in conftest.py.

packages/github-app/tests/conftest.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import os
+import sys
 from pathlib import Path
 from unittest.mock import MagicMock
 
@@ -10,7 +11,11 @@ import httpx
 import pytest
 import stamina
 
-from tests.helpers import FAKE_RSA_PEM, WEBHOOK_SECRET
+sys.path.insert(0, str(Path(__file__).resolve().parent))
+
+from helpers import FAKE_RSA_PEM, WEBHOOK_SECRET, sign_payload  # noqa: E402
+
+__all__ = ["FAKE_RSA_PEM", "WEBHOOK_SECRET", "sign_payload"]
 
 
 @pytest.fixture(autouse=True, scope="session")

packages/github-app/tests/test_app.py

@@ -7,7 +7,7 @@ import json
 from pathlib import Path
 from unittest.mock import AsyncMock, patch
 
-from tests.helpers import sign_payload
+from helpers import sign_payload
 
 
 async def test_health_check(async_client):

packages/github-app/tests/test_auth.py

@@ -11,7 +11,7 @@ from github_app.auth import (
     get_installation_token,
     verify_signature,
 )
-from tests.helpers import WEBHOOK_SECRET
+from helpers import WEBHOOK_SECRET
 
 
 def test_generate_jwt_structure(mock_config):

packages/github-app/tests/test_config.py

@@ -9,7 +9,7 @@ from unittest.mock import patch
 import pytest
 
 from github_app.config import Config, default_plugin_dir, load_private_key
-from tests.helpers import FAKE_RSA_PEM
+from helpers import FAKE_RSA_PEM
 
 
 def test_load_private_key_from_env():