perf(onedrive): use async httpx for token refresh

Replaces the synchronous `requests.post` and `requests.get` calls in
`app/api/onedrive.py:test_onedrive_token` with an asynchronous
`httpx.AsyncClient` implementation. This unblocks the FastAPI event loop
when this endpoint is hit.

Tests were updated to mock `httpx.AsyncClient` and a sync wrapper using `asyncio.run` was added to integration tests to maintain test coverage without massive test refactoring.

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

benchmark_onedrive.py

@@ -0,0 +1,69 @@
+import asyncio
+import time
+import httpx
+from unittest.mock import patch, MagicMock, AsyncMock
+from app.api.onedrive import test_onedrive_token
+from app.config import settings
+
+settings.onedrive_refresh_token = "dummy"
+settings.onedrive_client_id = "dummy"
+settings.onedrive_client_secret = "dummy"
+
+class DummyRequest:
+    def __init__(self):
+        self.session = {"user": "dummy"}
+
+async def run_benchmark(func_name, mock_post, mock_get):
+    mock_post_resp = MagicMock()
+    mock_post_resp.status_code = 200
+    mock_post_resp.json.return_value = {
+        "access_token": "dummy_access",
+        "expires_in": 3600
+    }
+    mock_post.return_value = mock_post_resp
+
+    mock_get_resp = MagicMock()
+    mock_get_resp.status_code = 200
+    mock_get_resp.json.return_value = {
+        "displayName": "Test User",
+        "userPrincipalName": "test@example.com"
+    }
+    mock_get.return_value = mock_get_resp
+
+    start_time = time.time()
+    for _ in range(100):
+        await test_onedrive_token(DummyRequest())
+    end_time = time.time()
+    print(f"{func_name} took {end_time - start_time:.4f} seconds")
+
+async def run_benchmark_async(func_name, mock_post, mock_get):
+    mock_post_resp = MagicMock()
+    mock_post_resp.status_code = 200
+    mock_post_resp.json = MagicMock(return_value={
+        "access_token": "dummy_access",
+        "expires_in": 3600
+    })
+    mock_post.return_value = mock_post_resp
+
+    mock_get_resp = MagicMock()
+    mock_get_resp.status_code = 200
+    mock_get_resp.json = MagicMock(return_value={
+        "displayName": "Test User",
+        "userPrincipalName": "test@example.com"
+    })
+    mock_get.return_value = mock_get_resp
+
+    start_time = time.time()
+    for _ in range(100):
+        await test_onedrive_token(DummyRequest())
+    end_time = time.time()
+    print(f"{func_name} took {end_time - start_time:.4f} seconds")
+
+
+@patch('app.api.onedrive.requests.get')
+@patch('app.api.onedrive.requests.post')
+def benchmark_sync(mock_post, mock_get):
+    asyncio.run(run_benchmark("Sync requests (baseline)", mock_post, mock_get))
+
+if __name__ == "__main__":
+    benchmark_sync()