Fix mypy errors from D3.4 and the luma module split

The compare-and-swap snapshots are proven non-None before **unpacking.
Event discovery now imports luma_events after luma.py was split.

Author: Snapshot Budgets

scripts/build_luma_event_identities.py

@@ -79,7 +79,7 @@ def build(*, luma_source: Path) -> dict[str, Any]:
         EXISTING_EVENT_NONE,
         ExistingEventIndex,
     )
-    from scripts.prod.registration_sources.luma import discover_luma_events
+    from scripts.prod.registration_sources.luma_events import discover_luma_events
 
     discovered = discover_luma_events(luma_source)
     index = ExistingEventIndex()

scripts/prod/account_reconciliation/__init__.py

@@ -888,6 +888,7 @@ def _apply_one_mapping(
             identity_state=IdentityState.States.ABSORBED,
         )
     else:
+        assert source_identity_snapshot is not None
         source_identity_updated = IdentityState.objects.filter(
             user_id=source.pk,
             **source_identity_snapshot,
@@ -933,6 +934,7 @@ def _apply_one_mapping(
             identity_state=IdentityState.States.ACTIVE,
         )
     else:
+        assert survivor_identity_snapshot is not None
         survivor_identity_updated = IdentityState.objects.filter(
             user_id=survivor.pk,
             **survivor_identity_snapshot,
@@ -955,6 +957,7 @@ def _apply_one_mapping(
             if field in _LEARNER_PROFILE_FIELDS
         }
         if profile_updates:
+            assert survivor_profile_snapshot is not None
             survivor_profile_updated = LearnerProfile.objects.filter(
                 user_id=survivor.pk,
                 **survivor_profile_snapshot,