M8-T03: adopt DSMR history into meter sources

tests/test_meter_sources.py

@@ -139,7 +139,9 @@ def test_populated_revision_14_upgrades_to_meter_source_head_with_audit(tmp_path
     finally:
         engine.dispose()
 
-    command.upgrade(config, "head")
+    # This T01 fixture intentionally audits the schema-only revision 15.
+    # Revision 16 has its own DSMR-history adoption fixture.
+    command.upgrade(config, "20260822_15_meter_sources")
 
     engine = _engine_with_foreign_keys(database_url)
     try:
@@ -187,7 +189,7 @@ def test_populated_revision_14_upgrades_to_meter_source_head_with_audit(tmp_path
         assert cost_fks["contract_version_id"]["referred_table"] == "energy_contract_version"
         assert cost_fks["source_binding_id"]["referred_table"] == "meter_source_binding"
 
-        command.upgrade(config, "head")
+        command.upgrade(config, "20260822_15_meter_sources")
         assert {
             table_name: engine.connect().execute(text(f"SELECT COUNT(*) FROM {table_name}")).scalar_one()
             for table_name in before_counts