feat(backend): CRUD jardins + tests

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/tests/conftest.py

@@ -0,0 +1,31 @@
+import pytest
+from fastapi.testclient import TestClient
+from sqlmodel import SQLModel, create_engine, Session
+from sqlmodel.pool import StaticPool
+
+import app.models  # noqa — force l'enregistrement des modèles
+from app.main import app
+from app.database import get_session
+
+
+@pytest.fixture(name="session")
+def session_fixture():
+    engine = create_engine(
+        "sqlite://",
+        connect_args={"check_same_thread": False},
+        poolclass=StaticPool,
+    )
+    SQLModel.metadata.create_all(engine)
+    with Session(engine) as session:
+        yield session
+
+
+@pytest.fixture(name="client")
+def client_fixture(session: Session):
+    def get_session_override():
+        yield session
+
+    app.dependency_overrides[get_session] = get_session_override
+    client = TestClient(app)
+    yield client
+    app.dependency_overrides.clear()