spp_change_request_v2: group-scope conflict detection crashes — conflict_mixin references nonexistent membership fields individual_id/group_id

[kneckinator]

Summary

ConflictDetectionMixin._get_group_member_ids (spp_change_request_v2/models/conflict_mixin.py, lines 282/289/292 on 19.0 @ 0341801) traverses spp.group.membership records via individual_id and group_id:

registrant.group_membership_ids.filtered(lambda m: not m.ended_date).mapped("individual_id.id")   # L282
group = membership.group_id                                                                        # L289
group.group_membership_ids.filtered(lambda m: not m.ended_date).mapped("individual_id.id")        # L292

But spp.group.membership names these many2ones individual and group (spp_registry/models/group_membership.py:16,22) — the _id suffix convention was not followed by this model. No module adds alias fields (the only other inheritor is spp_registry_group_hierarchy), confirmed against a live DB with spp_change_request_v2 installed.

Impact

Any change request whose type has an active conflict rule with scope = "group":

• Group registrant: crashes unconditionally with KeyError: 'individual_id' — even for a group with zero members, since mapped() resolves the field name via records._fields[name] before iterating (odoo/orm/models.py __getitem__).
• Individual registrant: crashes with the first non-ended membership (membership.group_id → AttributeError), i.e. exactly when the group-scope rule is supposed to do its job. An individual with no memberships happens to work, which is why the existing test passes.

Group-scope conflict rules are therefore unusable: enabling one makes CR creation/conflict detection raise for every registrant that actually belongs to a group.

Why tests don't catch it

test_conflict_detection_extended.py::test_group_scope_same_household_members calls _get_group_member_ids directly on an individual with zero memberships, so the loop body and both mapped() calls never execute. (The test's own comment notes membership creation was left "implementation-dependent".)

Fix

Rename the three accesses to the actual field names (individual, group) and extend the test to cover a group registrant with members and an individual with a membership.

Found while reviewing #418 (out of scope there — pre-existing on 19.0).