test: add performance testing tool for concurrent imports

[kojiromike]

Summary

Add a performance testing tool to validate concurrent vocabulary imports across multiple OpenEMR sites.

Background

The CLI supports database locking to prevent concurrent imports to the same site. We need a way to test:

• Concurrent imports to different sites work correctly in parallel
• Lock contention behaves as expected when multiple processes target the same site
• Performance characteristics under load

Tasks

• Create Docker Compose configuration for multiple OpenEMR sites
• Build a test harness script that spawns concurrent import processes
• Add metrics collection (timing, memory, success/failure rates)
• Document performance testing procedures

Proposed approach

1. Extend compose.yml to support multiple sites (e.g., site1, site2, site3)
2. Create a task perf:test command that:
   • Spins up N OpenEMR sites
   • Runs concurrent imports with configurable parallelism
   • Reports timing and success metrics
3. Test scenarios:
   • N parallel imports to N different sites (should all succeed)
   • N parallel imports to same site (should serialize via locking)
   • Mixed workload with varying file sizes

Notes

• Performance tests should not run in CI (too slow/resource-intensive)
• Consider using small test fixtures rather than real vocabulary files
• May want to measure memory usage for large imports