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

backend/scripts/smoke_e2e.py

@@ -1,7 +1,8 @@
 """Manual end-to-end smoke: real LFX + real API, frontend-shaped calls.
 
 Usage (from backend/):
-    TEST_DATABASE_URL=postgresql+psycopg://... uv run python scripts/smoke_e2e.py
+    uv run python scripts/smoke_e2e.py
+Runs the API against a throwaway SQLite file and an ephemeral LFX pass.
 Exits non-zero on any unexpected status/body.
 """
 
@@ -11,7 +12,7 @@ import json
 import os
 import subprocess
 import sys
-import time
+import tempfile
 import urllib.request
 from pathlib import Path
 
@@ -54,17 +55,31 @@ def check(name: str, cond: bool, detail: str = "") -> None:
 
 
 def main() -> None:
+    tmp = Path(tempfile.mkdtemp(prefix="kirche-smoke-"))
     flow_dir = Path("/tmp/smoke-e2e-flows")
     flow_dir.mkdir(exist_ok=True)
     (flow_dir / "seed.json").write_text(
         (FIXTURES / "simple_rule.json").read_text()
     )
+    # Migrate a throwaway SQLite schema to head before starting the API.
+    from alembic import command as alembic_command
+    from alembic.config import Config
+
+    db_url = f"sqlite:///{tmp / 'smoke.db'}"
+    cfg = Config()
+    cfg.set_main_option("script_location", str(BACKEND / "migrations"))
+    cfg.set_main_option("sqlalchemy.url", db_url)
+    alembic_command.upgrade(cfg, "head")
+
     env = {
         **os.environ,
+        # lfx prefers LANGFLOW_API_KEY over LFX_API_KEY; the repo .env may set
+        # it. Clear it so the serve key below is the one we send.
+        "LANGFLOW_API_KEY": "",
         "LFX_API_KEY": LFX_KEY,
-        "DATABASE_URL": os.environ["TEST_DATABASE_URL"],
+        "DATABASE_URL": db_url,
+        "FLOWS_WATCH_ENABLED": "false",
         "LFX_URL": f"http://127.0.0.1:{LFX_PORT}",
-        "LFX_API_KEY": LFX_KEY,
         "CALLBACK_BASE_URL": f"http://127.0.0.1:{API_PORT}",
     }
     lfx = subprocess.Popen(