Task: Migrate the remaining 10 lookup_entity models to domain_entity; retire ores.codegen.lookup_entity

(Describe what user-visible-or-internal change this task produces.)

(Implementation strategy. Written when work starts; key decisions are distilled into the parent story's * Decisions at close, but the plan itself stays — it is the historical record of what we did.)

Warning carried over from 464B5EC6's review round: lei_entity and lei_relationship (both in this task's scope) set has_artefact_insert_fn: true and genuinely depend on it – sql_schema_artefact_create.mustache (line 43) renders \{\{#entity.has_artefact_insert_fn\}\} to generate their artefact-table insert function, wired in via get_schema_template_mappings() for lookup_entity/schema-model entities. domain_entity_to_table_context()=/ =get_domain_entity_template_mappings() have no equivalent hook for this flag today. Migrating these two the same way 464B5EC6 migrated the 5 DQ entities (which all had has_artefact_insert_fn: false, so the gap never surfaced) would silently drop their artefact insert function. Before migrating lei_entity=/=lei_relationship, either port has_artefact_insert_fn support into domain_entity's SQL template set, or verify/accept the behaviour change explicitly – don't assume dropping it is safe by analogy with the other 8 entities.

Manual QA scenarios (scaffolded via compass add test_scenario, run through the QA Validation Runner panel) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.