perf(react-dom): bound server style name cache

[leno23]

Summary

This bounds the module-level styleNameCache used by processStyleName in the React DOM server renderer.

The cache normally contains a small fixed set of style property names, but it is currently unbounded for the lifetime of a long-running SSR process. This change clears the cache if it grows beyond 1024 unique keys, preserving the existing fast path for normal cases while avoiding pathological retention of unbounded user-generated style names.

Test Plan

• Not run locally yet; opening as draft for initial feedback.
• Intended checks before marking ready:
  • yarn test packages/react-dom
  • relevant React DOM server/Fizz tests
  • microbenchmark if maintainers want data for the cache cap tradeoff

Notes

I chose a simple clear-on-limit strategy instead of LRU to avoid adding per-access overhead to the hot path.

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