[agrawalmilin9]

Summary

Addresses review feedback from the road-based pickup ETA implementation.

Changes

• Moved synchronous dispatch matching to asyncio.to_thread() to avoid blocking the event loop.
• Added a bounded LRU cache for turn costs.
• Protected shared turn-cache operations with a thread lock.
• Added tests for LRU eviction and restricted-turn caching.
• Added backend tests for RouteService initialization and road-based ETA estimation.
• Removed the UTF-8 BOM from the benchmark script.

Testing

• pytest tests backend/tests -q
• 129 passed, 1 skipped, 16 subtests passed
• git diff --check passed.

Related

Follow-up to PR #34 — Optimize road-based pickup ETA matching.