perf: batch scheduling reconciliation and add widget

tests/test_service.py

@@ -93,6 +93,23 @@ from govoplan_scheduling.backend.runtime import configure_runtime
 
 class SchedulingServiceTests(unittest.TestCase):
     def setUp(self) -> None:
+        fixed_now = datetime(2026, 7, 19, 12, tzinfo=timezone.utc)
+        self.now_patches = (
+            patch(
+                "govoplan_scheduling.backend.service._now",
+                return_value=fixed_now,
+            ),
+            patch(
+                "govoplan_poll.backend.service._now",
+                return_value=fixed_now,
+            ),
+            patch(
+                "govoplan_poll.backend.participation_service._now",
+                return_value=fixed_now,
+            ),
+        )
+        for now_patch in self.now_patches:
+            now_patch.start()
         registry = PlatformRegistry()
         registry.register(get_poll_manifest())
         registry.register(get_calendar_manifest())
@@ -125,6 +142,8 @@ class SchedulingServiceTests(unittest.TestCase):
         self.session: Session = self.Session()
 
     def tearDown(self) -> None:
+        for now_patch in reversed(self.now_patches):
+            now_patch.stop()
         self.session.close()
         Base.metadata.drop_all(
             self.engine,