Changes to match the working vendor marketplace import:
1. Make POST endpoint async (was sync)
2. Use positional args for background task (was keyword args)
3. Import process_marketplace_import at top of file (was inside function)
4. Fix route order: /stats now defined BEFORE /{job_id}
to avoid FastAPI route conflicts
5. Remove unused admin_service import
These changes align the admin endpoint with the vendor endpoint
pattern that was already working correctly.
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Co-Authored-By: Claude <noreply@anthropic.com>