[Issue]: Add queued exports for large activity datasets

[MrAdder]

Issue Type

Feature request

Summary

Support queued export generation so large audit exports do not rely solely on direct request-response execution.

Problem / Context

Large datasets can make synchronous exports slow or fragile. Queued export support would better serve larger deployments and long-running reporting jobs.

Proposed Solution

Add an optional queued export path for large activity datasets, while keeping the current direct export flow available where appropriate.

Acceptance Criteria

• Large exports can be handled asynchronously through the queue.
• The direct export flow still works for smaller datasets.
• Users have clear feedback about queued export status or output location.

Implementation Notes

Think through queue dependencies, storage location, cleanup, and whether this should be opt-in through config.

Testing Notes

Add tests around queued export dispatch and output generation, and verify the non-queued path still works.

Additional Context

This is one of the most valuable scale-oriented improvements for later 1.x.