chore(changeset): add changeset for expand where propagation fix

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: os-zhuang

.changeset/expand-where-propagation.md

@@ -0,0 +1,10 @@
+---
+"@objectstack/objectql": patch
+"@objectstack/spec": patch
+---
+
+Honor a nested `where` filter inside `expand` on lookup/master_detail expansion.
+
+The expand post-processor batch-loads related records with an `id $in [...]` query but never merged the nested QueryAST `where`, so a documented `expand: { rel: { where: {...} } }` filter was silently ignored and every related record came back. The nested filter is now AND-merged into the batch query via an explicit `$and` group (`{ $and: [{ id: { $in } }, nestedAST.where] }`) — robust against a nested filter that itself keys `id` or uses a top-level `$or`/`$and`, where a shallow spread would clobber or reorder the constraint.
+
+`limit`/`offset`/`orderBy` remain intentionally not honored on the expand path: it batch-loads every parent's related records in one `$in` query and re-keys them per parent by foreign key, so a per-parent page size or ordering can't be expressed there. Docs and the schema `describe()` are updated to match, with a guard test asserting `limit`/`offset` are not pushed into the expand query.