feat: flow engine data layer with tests

- SQLModel tables: flow_definitions/versions/runs, approval_tasks
- Alembic setup with autogenerate (sqlmodel types fixed via script.py.mako)
- Settings extended (shared root .env), db engine/session helpers
- pytest suite: conftest with isolated test DB, 5 model tests green

backend/pyproject.toml

@@ -4,9 +4,12 @@ version = "0.1.0"
 description = "Kirche Einfach - KI-gestuetzte Verwaltungsplattform fuer Kirche"
 requires-python = ">=3.12"
 dependencies = [
+    "alembic>=1.14",
     "fastapi[standard]>=0.115.0",
-    "django>=5.1",
+    "httpx>=0.28",
+    "psycopg[binary]>=3.2",
     "pydantic-settings>=2.0",
+    "sqlmodel>=0.0.24",
     "uvicorn[standard]>=0.30.0",
 ]
 
@@ -17,3 +20,16 @@ build-backend = "uv_build"
 [tool.uv.build-backend]
 module-name = "app"
 module-root = ""
+
+[tool.pytest.ini_options]
+asyncio_mode = "auto"
+testpaths = ["tests"]
+
+[dependency-groups]
+dev = [
+    "lfx==1.12.0",
+    "pytest>=8",
+    "pytest-asyncio>=0.24",
+    "pytest-cov>=6",
+    "respx>=0.22",
+]