Move the site to Solid 2 and the current component library - #8

Why

@pathscale/ui 1.2.11 is far behind. Reaching the current release means moving the whole stack, because the library is unusable on Solid 1: solid-layouts imports helpers only the newer major exports, and rspack hard-errors on them at link time even though the library guards the call at runtime. 2.5.x is not a middle ground for the same reason.

What changed

Runtime and toolchain

• solid-js 2.0.0-rc.0, @solidjs/router 2.0.0-next.16, solid-layouts 0.2.0, @pathscale/ui 2.6.2.
• JSX moved to @solidjs/web, so jsxImportSource and the render import move with it.
• Drops @rsbuild/plugin-solid: it pins babel-preset-solid@^1.9.12, the Solid 1 compiler, which emits a use helper and a solid-js/web specifier that Solid 2 removed. Babel drives the Solid 2 preset directly instead.
• Adds rsbuild-plugin-solid-layouts, the library's own integration, and resolves solid-layouts to the Solid 2 backend it ships behind a /solid-2 subpath while its default entry stays on Solid 1.
• Removes the @refresh reload pragma, which pulled Solid 1 refresh codegen into the dev build.

Call sites

• variant="primary" becomes variant="solid" with flavor="primary"; isIconOnly becomes width="square"; Icon takes src rather than name.
• The router no longer ships Router, Route or A, so routes are declared through createRouter and links are plain anchors.
• createEffect takes a compute function and an effect function, and onMount is gone, so both call sites move to the new shape.

Verification

• bun run typecheck, bun run lint (exit 0) and bun run build all pass. The dev build reports zero resolution errors.
• Driven in a real browser against bun run dev, on @pathscale/ui@2.6.2 installed from npm rather than a local build: /, /spec, /syntax and /vignette all render with zero console errors, the home page tabs switch panels, the theme toggle flips light and dark and persists, and client-side navigation works without a full page load.

The home page depended on a Solid 2 fix in the component library (pathscale/ui#247, released as 2.6.2); before it, Tabs halted the reactive system and the page rendered blank.