[Feature Request] groupBy and aggregate should support include #2366
Description
Is your feature request related to a problem? Please describe.
When using the query API groupBy and aggregate currently operate only on fields of the base model. There is no way to join related models using include or similar semantics. This becomes a problem when aggregating records by a value that lives on a related table and is not the primary key. In practice this means I can group by a foreign key id but then must perform an additional query to resolve meaningful fields like a symbol or code from the related table, which adds extra round trips and complexity.
Describe the solution you'd like
Extend groupBy and aggregate to support include so that related models can be joined as part of the aggregation query. This would allow grouping or aggregating based on fields from related tables and returning those related fields directly in the result set. Conceptually this would mirror how include works for find queries while still respecting ZenStack access policies.
Describe alternatives you've considered
The main workaround is to group by the foreign key id and then issue a second query to fetch the related records and manually merge the results. Another option is denormalizing the related field into the base table, but that introduces duplication and consistency issues. Neither approach is ideal compared to first class join support in groupBy and aggregate.
Additional context
This feature would help reduce query count and improve performance for reporting and analytics style use cases. It would also bring groupBy and aggregate closer in parity with common ORM and SQL patterns where joins are available during aggregation.