fix: prevent browser freeze when tessellating >50k vertices (#8219 )

[Nixxx19]

Resolves #8219

Summary

• Adds a one‑time confirmation prompt before tessellating very large TESS shapes (>50,000 vertices) to avoid browser freezes in libtess during _triangulate().
• Cancel: skips tessellation and draws nothing for that shape (no TRIANGLE_FAN fallback), keeping behavior explicit and predictable.
• OK: remembers the choice for the lifetime of the renderer via _largeTessellationAcknowledged and tessellates normally without prompting again.
• Respects p5.disableFriendlyErrors / minified builds: when friendly errors are disabled, tessellation always runs with no prompt.

Tests

• Adds / updates WebGL unit tests in test/unit/webgl/p5.RendererGL.js to cover:
  • Prompting once for large shapes and including the vertex count in the message.
  • Skipping tessellation entirely on cancel (no TRIANGLE_FAN fallback).
  • Only prompting once per renderer when the user approves.
  • Skipping the prompt when p5.disableFriendlyErrors is true.
  • Normal tessellation behavior for shapes below the 50k‑vertex threshold.

Screenshot

PR Checklist

• npm run lint passes
• Inline reference is included / updated (not applicable – bug fix only)
• Unit tests are included / updated

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