docs: record product search integration

.project-docs/40-domain/business-rules.md

@@ -20,6 +20,7 @@
 - Passenger overwrite requires confirmation when target ERP rows are occupied; after `full_replace + confirmed=true`, every attachment-specified sequence is written even when values are unchanged.
 - A single strict `领队` row supplies leader contact; ambiguous, incomplete, duplicate, or structurally inconsistent leader data fails closed.
 - Shared-mother-plan `整团游客信息` export is only `shared_plan + visitor-list + tid-only`; independent and concrete shared-child visitor lists remain `did+tid`.
+- Scatter-plan creation and independent batch-order creation resolve products from the currently loaded candidates first. If that is not uniquely resolvable, the adapter must dispatch the form's native non-empty `S_chanpinming` lookup using the complete product name or a name with only a trailing numeric duration shorthand such as `10D`, `8天`, or `8D7N` removed, wait for Ajax settlement, and run the same deterministic local unique matcher. Only one bounded empty-query compatibility reload may follow; zero or multiple matches still stop before product selection or any write.
 - Real writes require unique resolution, exact page identity, ownership, write projection, explicit server response, and action-specific completion evidence.
 - Current business capability and verification status come from active source/contracts and the lifecycle release gate, never from archive wording.