9c984b137f
## Summary - **`isValidCountryCode`** was using `Array.includes()` on ~250 country codes (O(n) per call). Replaced with a `Set.has()` lookup (O(1)). - **`getCountryCodesForCallingCode`** was iterating all ~250 countries and calling `getCountryCallingCode()` on each one **every invocation**. Replaced with a precomputed `Map<callingCode, CountryCode[]>` built once at module load (O(1) per call). Both functions are called from `transformPhonesValue` on every phone field mutation, causing cumulative overhead visible in profiling (p95 self-time ~20-35ms). ## Test plan - [ ] Verify phone field creation/update still works correctly (country code validation, calling code resolution) - [ ] Verify spreadsheet import with phone fields still validates properly - [ ] Confirm no regression in `isValidCountryCode` or `getCountryCodesForCallingCode` behavior Made with [Cursor](https://cursor.com) Co-authored-by: Cursor <cursoragent@cursor.com>