Optimize parsed meshes and renderer follow-ups

[agustin-littlehat]

Summary

• Optimize parsed mesh results by default and expose the core optimizer through React/Vue barrels.
• Move gallery/workbench mesh cleanup onto the shared core optimizer and add optimizer corpus/variant benchmarks.
• Fix corner-shape triangle paint ownership and share vanilla mesh hit testing across select/transform controls.

Tests

• pnpm test && pnpm build