test(sql-orm-client): declare junction namespaceId in the shared M:N contract helper

resolveThrough now requires the contract through block to carry the
junction's namespaceId; without it the relation resolves as non-M:N and
the filter EXISTS tests assert the wrong shape.

Signed-off-by: Alexey Orlenko's AI Agent <robot@aqrln.net>

Author: tensordreams

packages/3-extensions/sql-orm-client/test/helpers.ts

@@ -375,6 +375,7 @@ export function buildManyToManyContract(opts: {
                   on: { localFields, targetFields: targetColumns },
                   through: {
                     table: junctionTable,
+                    namespaceId: 'public',
                     parentColumns,
                     childColumns,
                     targetColumns,