chore: migrate postprocessing docs to Nuxt + Nuxt UI

[alvarosabu]

Summary

Migrate apps/postprocessing-docs-vitepress to a new Nuxt v4 + Nuxt UI v4 docs app at apps/postprocessing-docs, mirroring the cientos-docs architecture with a dedicated pink/magenta theme sourced from the playground's tres-postprocessing color (#FF7BAC).

Closes TRES-272

What's in

• New app scaffold duplicated from apps/docs-boilerplate and rebranded (@tresjs/post-processing workspace dep, pink primary palette anchored at -300, postprocessing GitHub/footer/TOC links, LLM sections for Getting Started / API / Advanced)
• 34 demo components ported from VitePress → Nuxt with the cientos MDC pattern:
  • 29 pmndrs effects under app/components/pmndrs/ (Ascii, Bloom, Chromatic Aberration, Depth of Field, God Rays, Glitch, Kuwahara, Outline, Pixelation, Vignette, Shock Wave, etc.)
  • 5 three native effect demos under app/components/three/ (Glitch, Halftone, Pixelation, Smaa, UnrealBloom)
  • Shared DocsDemo.vue wrapper (ClientOnly + Suspense + optional Leches panel via `controls` prop)
• 38 markdown pages with Nuxt Content MDC syntax:
  • Landing hero + getting-started (introduction + installation) + API overview + advanced guide
  • 29 pmndrs effect pages + 6 three native effect pages + `output.md` (doc-only)
• Canonical Leches binding fix: destructured `useControls` refs bound per-prop instead of broken `v-bind="reactiveObject"` pattern (caught in code review before replicating 27×)
• Deploy config (`netlify.toml`)

What's out of scope (follow-up)

• Deleting `apps/postprocessing-docs-vitepress` (after production flip)
• Updating links in `apps/docs` to point at the new site (after DNS flip)
• Pink `-400` → `-900` visual QA (shades are educated-guesses anchored at `#FF7BAC = -300`; tune via uicolors.app if needed)
• Some source features dropped due to missing deps: gsap animations on FishEye/ColorAverage/ColorDepth/ShockWave replaced with `useLoop`/static; FXAA split-screen simplified to single canvas

Test plan

• `pnpm --filter postprocessing-docs lint` — clean ✅
• `pnpm --filter postprocessing-docs typecheck` — only pre-existing `ProseA.vue:29` boilerplate error ✅
• `pnpm --filter postprocessing-docs build` — all 37 pages prerender, `llms.txt` + `llms-full.txt` generate ✅
• `pnpm --filter postprocessing-docs dev` — landing renders with pink hero, sidebar lists all effects, each demo page renders 3D scene + Leches controls (where applicable)
• Navigate `/api/pmndrs/bloom` — hotpink emissive sphere renders with visible bloom glow + 4 sliders that actually affect the scene (intensity, radius, luminanceThreshold, luminanceSmoothing)
• Navigate `/api/three/unreal-bloom` — demo renders with Leches panel
• Navigate `/advanced/you-might-not-need-post-processing` — renders
• Dark-mode toggle works across pages

[netlify]

✅ Deploy Preview for cientos-tresjs ready!

Name	Link
🔨 Latest commit	7c88e3d
🔍 Latest deploy log	https://app.netlify.com/projects/cientos-tresjs/deploys/69f10d2fd36d8e0008d94599
😎 Deploy Preview	https://deploy-preview-1406--cientos-tresjs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[netlify]

✅ Deploy Preview for tresjs-docs ready!

Name	Link
🔨 Latest commit	7c88e3d
🔍 Latest deploy log	https://app.netlify.com/projects/tresjs-docs/deploys/69f10d2f1a864e0008699c3f
😎 Deploy Preview	https://deploy-preview-1406--tresjs-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[netlify]

✅ Deploy Preview for tresjs-lab ready!

Name	Link
🔨 Latest commit	7c88e3d
🔍 Latest deploy log	https://app.netlify.com/projects/tresjs-lab/deploys/69f10d3112d2170008cbc117
😎 Deploy Preview	https://deploy-preview-1406--tresjs-lab.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[pkg-pr-new]

Open in StackBlitz

@tresjs/cientos

npm i https://pkg.pr.new/@tresjs/cientos@1406

@tresjs/core

npm i https://pkg.pr.new/@tresjs/core@1406

@tresjs/eslint-config

npm i https://pkg.pr.new/@tresjs/eslint-config@1406

@tresjs/leches

npm i https://pkg.pr.new/@tresjs/leches@1406

@tresjs/nuxt

npm i https://pkg.pr.new/@tresjs/nuxt@1406

@tresjs/post-processing

npm i https://pkg.pr.new/@tresjs/post-processing@1406

commit: 7c88e3d