feat: await referenced fonts before lazy draw

[mlightcad]

Summary

• Add FontManager.awaitFontsBeforeDraw and per-draw { awaitFonts } so lazy loading can wait for content/style fonts before building geometry (single draw instead of fallback + fontLoaded redraw).
• Propagate the flag through UnifiedRenderer / worker pool (setAwaitFontsBeforeDraw), and make requestFonts return an awaitable promise.
• Wire an example checkbox and cover await / options / worker sync in remote font-loading tests.

Test plan

• npm test --workspace=@mlightcad/mtext-renderer -- test/worker/render-remote-font-loading.test.ts
• Example: enable Lazy Font Loading + Await Fonts Before Draw, Release Fonts, then Render — first paint should wait and not progressively redraw on fontLoaded
• Example: Lazy ON, Await OFF — confirm fallback-then-redraw on fontLoaded still works
• Worker and main-thread render modes both respect the await flag