Resolves FOREIGN KEY constraint failed (500) on DELETE /api/admin/users/:id
and DELETE /api/auth/me when the target user had rows in trip_members.invited_by,
share_tokens.created_by, budget_items.paid_by_user_id, journeys.user_id,
journey_entries.author_id, journey_contributors.user_id, or
journey_share_tokens.created_by — none of which had ON DELETE clauses.
Introduces deleteUserCompletely() in userCleanupService.ts which wraps all
cleanup and the final DELETE FROM users in a single transaction. Both
adminService.deleteUser and authService.deleteAccount now call it instead of
the bare DELETE. Tests ADMIN-005b and AUTH-040 cover all reference types
including notification sender/recipient and notice dismissals.
jubnl
185a41831a