Site overhaul, Tetris tutorial chapter, and library catch-up from fixes

[bigmistqke]

What's in this PR

A new docs site for solid-three (site/, ~21k lines, 93 files) plus a small follow-up refactor of the renderer-type default. The library/test-infrastructure work that came in via the recent fixes merge — gl-prop flat refactor, browser-mode testing migration, createThree canvas swap, etc. — is not described below; it's its own concern and reviewable separately.

The docs site

Scaffolded under site/ with SolidStart and SolidBase, rendered with MDX. Every code sample is a live <Demo> — a small wrapper around @bigmistqke/repl that compiles the snippet with babel-preset-solid and runs it in an iframe; the reader can edit the source in-place. Two top-level sections:

Tutorial (nine chapters)

1. Your first scene — Canvas, <T.Mesh>, the smart-prop pipeline.
2. Props and children — nesting, transforms, args, reactive props.
3. Control flow — <Show>, <For>, <Index>, <Switch>/<Match>, <Suspense>.
4. Pointer events — click, hover, stopPropagation, onClickMissed.
5. useFrame — signal form, imperative form, priority ordering.
6. Loaders & Resource — useLoader, <Resource>, loader cache.
7. Portal — escape transforms; render-to-texture.
8. Tetris — built across three demos (render → gravity+keys → lines+score). The chapter's punchline: "game development is state management; Solid is a state manager that happens to render <T.Mesh>."
9. A peek at WebGPU — WebGPURenderer factory, TSL basics, a TSL uniform-driven slider.

API reference

Ported and rewritten from the README into per-export pages, organised by component / hook / event / utility (16 pages). Notable rewrites:

• Canvas — flat r3f-style gl prop documented, with an explicit note that constructor params are applied once at first construction and are never re-read (because canvas.getContext is idempotent — to swap, unmount and remount <Canvas>). Defaults table covers frameloop, gl, shadows, tone-mapping, color-space.
• useProps — rewritten to match the actual coercion order in src/props.ts.
• Entity / createEntity — moved off the T page where it didn't belong.
• Events overview — consolidated event-object shape, intersection fields, smart-prop pipeline.

Home page

A 3D hero scene of SOLID THREE letters dropped with cannon-es physics, cursor repulsion, click-to-punch, camera drift, fake contact shadows, studio reflection. A toggle lazy-mounts a <Demo> editor over the scene so the home page doubles as a REPL into its own source.

<Demo> component

The piece that makes the whole site tick. Wraps @bigmistqke/repl, pre-bundles the local solid-three for the iframe, gates the editor open on click, syncs the editor theme with the site's light/dark mode, syntax-highlights via tm-textarea, surfaces compile errors without killing the iframe, and bakes color-scheme into the iframe HTML at creation so there's no white flash in dark mode.

Renderer type default (small library follow-up)

The fixes merge left ResolvedRenderer defaulting to the open Renderer union, which forced every project to declare a Register augmentation just to call WebGLRenderer-specific methods on useThree().gl. This PR flips the default:

• ResolvedRenderer defaults to WebGLRenderer — the common case is friction-free; users on other renderers opt in via Register.
• Register / Renderer / ResolvedRenderer re-exported at the top level so declare module "solid-three" { interface Register { ... } } works directly (previously the symbols were only accessible via the S3 namespace, so augmentation didn't merge).
• Site widens back to the open union via a local solid-three.d.ts since the site demos both WebGL and WebGPU renderers.
• Tests widen back in tests/setup.ts so mock RendererLike renderers in test fixtures keep type-checking.

This is the only library change in this PR; everything else under src/ was already in fixes.

Process / docs

Specs and implementation plans for the bigger pieces of work (tutorial structure, hero splash REPL, tetris chapter) live under docs/superpowers/{specs,plans}/.

Test plan

• pnpm test — 9 files, 151 passed, 2 todo, 0 failures.
• pnpm exec tsc --noEmit — clean apart from two pre-existing, unrelated errors (demo.tsx babel-preset, vite.config.ts extensionAlias drift).
• pnpm build — both ESM and DTS build successfully.
• cd site && pnpm dev — walk the tutorial chapters end to end, exercise the API reference pages, confirm the hero scene plays.