Fix: test_map_api.py DB isolation — set CANTEEN_DB_PATH inside client fixture

Previously relied on module-level env var which got overwritten
when frontend tests' conftest.py test_db_path fixture ran first.
Now explicitly sets env var inside client fixture + invalidates
caches before import. Also fixed importlib order.

tests/test_map_api.py

@@ -30,13 +30,15 @@ def clean_db():
 
 @pytest.fixture
 def client():
+    # Ensure isolated DB path (module-level env may be overwritten by other tests)
+    os.environ["CANTEEN_DB_PATH"] = str(TEST_DB)
     _clean_db()
+    import importlib
+    importlib.invalidate_caches()
     for mod in list(sys.modules.keys()):
         if mod == "server" or mod.startswith("server."):
             del sys.modules[mod]
     import server
-    import importlib
-    importlib.invalidate_caches()
     with TestClient(server.app) as tc:
         yield tc