Problem

BF-45686 fails test_api_version_compatibility with ID0065 because the create command includes the new $joinPlanCacheStats database-level planCacheRead privilege without its aggregation-stage identifier.

Root Cause

SERVER-131278 added the privilege in src/mongo/db/shard_role/ddl/create.idl. The equivalent entry in src/mongo/db/pipeline/aggregate_command.idl includes agg_stage: joinPlanCacheStats.

Fix

Add agg_stage: joinPlanCacheStats to the create privilege. This allows the IDL compatibility checker to treat the new stage independently when comparing prior releases, matching the established mechanism from [SERVER-86889|https://jira.mongodb.org/browse/SERVER-86889].

Acceptance Criteria

* test_api_version_compatibility no longer reports ID0065 for create.
* The database-scoped planCacheRead authorization requirement remains unchanged.