chore: add vite-rsc-unocss

[hi-ogawa]

Part of vitejs/vite-plugin-react#743

It looks like build is broken.

> vite build

vite v7.1.3 building SSR bundle for production...
[plugin unocss:global:build:scan] [unocss] "virtual:uno.css" is being imported multiple times in different files, using the first occurrence: "/home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/__uno.css"
[plugin unocss:global:build:scan] [unocss] "virtual:uno.css" is being imported multiple times in different files, using the first occurrence: "/home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/__uno.css" (x2)
✓ 54 modules transformed.
[plugin unocss:global:build:generate] [unocss] failed to find vite:css-post plugin. It might be an internal bug of UnoCSS
✓ built in 250ms
vite v7.1.3 building SSR bundle for production...
✓ 50 modules transformed.
✓ built in 223ms
vite v7.1.3 building SSR bundle for production...
[plugin unocss:global:build:scan] [unocss] "virtual:uno.css" is being imported multiple times in different files, using the first occurrence: "/home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/__uno.css"
[plugin unocss:global:build:scan] [unocss] "virtual:uno.css" is being imported multiple times in different files, using the first occurrence: "/home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/__uno.css" (x2)
✓ 54 modules transformed.
[plugin unocss:global:build:generate] [unocss] failed to find vite:css-post plugin. It might be an internal bug of UnoCSS
[plugin vite:reporter] 
(!) /home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/action.tsx is dynamically imported by virtual:vite-rsc/server-references but also statically imported by /home/hiroshi/code/personal/reproductions/vite-rsc-unocss/src/root.tsx, dynamic import will not move module into another chunk.

dist/rsc/assets/index-BRYPp0om.css    1.45 kB
dist/rsc/index.js                   472.04 kB
✓ built in 448ms
vite v7.1.3 building for production...
✓ 40 modules transformed.
dist/client/assets/index-BRYPp0om.css    1.45 kB │ gzip:  0.75 kB
dist/client/assets/client-B6VVadz3.js    0.19 kB │ gzip:  0.18 kB
dist/client/assets/index-Bx4hZ71J.js   213.10 kB │ gzip: 67.41 kB
✓ built in 401ms
vite v7.1.3 building SSR bundle for production...
✓ 50 modules transformed.
dist/ssr/assets/client-Te7tlATM.js      0.41 kB
dist/ssr/index.js                   1,352.92 kB
✓ built in 611ms

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This is worked around by adding top-level build outDir. Unocss doesn't support per-environment build config https://github.com/unocss/unocss/blob/1bcc90169a024b53844910f0df1bc5929fb8210b/packages-integrations/vite/src/modes/global/build.ts#L128

[hi-ogawa]

Here is a workaround.