fix(tests): align stale tests with current API + bypass identity-map cache

- test_recipes: split update test into in-place vs copy-on-write paths
  (PUT now updates in-place when current version has no measurements).
  Added _seed_measurement() helper to force copy-on-write where needed.
- test_tasks::reorder: expunge_all() between POST and GET so the shared
  test session re-fetches RecipeVersion.tasks instead of returning the
  cached collection. Prod uses one session per request, so identity-map
  staleness only affects tests.
- test_measure::save_measurement_proxy: payload aligned to current API
  (version_id is required; pass_fail/deviation are computed server-side).

All 179 tests green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/frontend/flask_app/tests/test_measure.py

@@ -61,7 +61,7 @@ class TestSaveMeasurement:
         mock_api_client.post.return_value = {
             "id": 1,
             "subtask_id": 10,
-            "task_id": 5,
+            "version_id": 3,
             "value": 9.95,
             "pass_fail": "pass",
         }
@@ -70,10 +70,8 @@ class TestSaveMeasurement:
             "/measure/save-measurement",
             json={
                 "subtask_id": 10,
-                "task_id": 5,
+                "version_id": 3,
                 "value": 9.95,
-                "pass_fail": "pass",
-                "deviation": 0.05,
             },
             content_type="application/json",
         )
@@ -86,7 +84,7 @@ class TestSaveMeasurement:
         """Missing required fields return 400."""
         resp = logged_in_client.post(
             "/measure/save-measurement",
-            json={"subtask_id": 10},  # missing task_id and value
+            json={"subtask_id": 10},  # missing version_id and value
             content_type="application/json",
         )
         assert resp.status_code == 400