feat: Add end-to-end tests for document upload pipeline and shared test utilities

- Introduced new test files for end-to-end testing of document uploads, including support for .txt, .md, and .pdf formats.
- Created shared fixtures and helper functions for authentication, document management, and cleanup.
- Added sample documents for testing purposes.
- Established a conftest.py file to provide reusable fixtures across test modules.

surfsense_backend/tests/conftest.py

@@ -0,0 +1,73 @@
+"""Root conftest — shared fixtures available to all test modules."""
+
+from __future__ import annotations
+
+import contextlib
+from collections.abc import AsyncGenerator
+
+import httpx
+import pytest
+
+from tests.utils.helpers import (
+    BACKEND_URL,
+    TEST_SEARCH_SPACE_ID,
+    auth_headers,
+    delete_document,
+    get_auth_token,
+)
+
+
+@pytest.fixture(scope="session")
+def backend_url() -> str:
+    return BACKEND_URL
+
+
+@pytest.fixture(scope="session")
+def search_space_id() -> int:
+    return TEST_SEARCH_SPACE_ID
+
+
+@pytest.fixture(scope="session")
+async def auth_token(backend_url: str) -> str:
+    """Authenticate once per session and return the JWT token."""
+    async with httpx.AsyncClient(
+        base_url=backend_url, timeout=30.0
+    ) as client:
+        return await get_auth_token(client)
+
+
+@pytest.fixture(scope="session")
+def headers(auth_token: str) -> dict[str, str]:
+    """Authorization headers reused across all tests in the session."""
+    return auth_headers(auth_token)
+
+
+@pytest.fixture
+async def client(backend_url: str) -> AsyncGenerator[httpx.AsyncClient]:
+    """Per-test async HTTP client pointing at the running backend."""
+    async with httpx.AsyncClient(
+        base_url=backend_url, timeout=180.0
+    ) as c:
+        yield c
+
+
+@pytest.fixture
+def cleanup_doc_ids() -> list[int]:
+    """Accumulator for document IDs that should be deleted after the test."""
+    return []
+
+
+@pytest.fixture(autouse=True)
+async def _cleanup_documents(
+    client: httpx.AsyncClient,
+    headers: dict[str, str],
+    cleanup_doc_ids: list[int],
+):
+    """
+    Runs after every test.  Deletes any document IDs that were appended to
+    the ``cleanup_doc_ids`` list during the test body.
+    """
+    yield
+    for doc_id in cleanup_doc_ids:
+        with contextlib.suppress(Exception):
+            await delete_document(client, headers, doc_id)