chore: switch to all-SQLite stack (drop Postgres service)

backend/tests/conftest.py

@@ -1,25 +1,22 @@
 """Shared pytest fixtures.
 
-Requires TEST_DATABASE_URL (a dedicated Postgres database, e.g. the
-`kirche_einfach_test` database from the compose stack). The URL is mapped
-onto DATABASE_URL *before* any app module is imported, so settings and the
-alembic env both target the test database. Never point this at production.
+Tests run on a throwaway SQLite file (no external database required).
+`DATABASE_URL` and `FLOWS_DIR` are pointed at a session temp dir *before* any
+app module is imported, so settings pick them up at import time. The app
+schema is migrated to head once per session via Alembic.
 """
 
 import os
+import tempfile
 from pathlib import Path
 
 import pytest
 
-TEST_DB_URL = os.environ.get("TEST_DATABASE_URL")
-if not TEST_DB_URL:
-    raise RuntimeError(
-        "TEST_DATABASE_URL is not set. Refusing to run tests without "
-        "an explicit test database (see .env.example)."
-    )
+TEST_AREA = Path(tempfile.mkdtemp(prefix="kirche-tests-"))
 
 # Must precede all `app.*` imports: Settings is instantiated at import time.
-os.environ["DATABASE_URL"] = TEST_DB_URL
+os.environ["DATABASE_URL"] = f"sqlite:///{TEST_AREA / 'test.db'}"
+os.environ["FLOWS_DIR"] = str(TEST_AREA / "flows")
 
 BACKEND_DIR = Path(__file__).resolve().parent.parent
 
@@ -115,6 +112,10 @@ def lfx_server(tmp_path_factory):
     env = {
         **os.environ,
         # lfx serve refuses to start without a serve key; requests need it too.
+        # get_api_key() prefers LANGFLOW_API_KEY over LFX_API_KEY, and the repo
+        # .env may put a real Langflow key in the environment — clear it so the
+        # test key below is the one the client sends.
+        "LANGFLOW_API_KEY": "",
         "LFX_API_KEY": "test-lfx-key",
     }
     proc = subprocess.Popen(