docs: fix build issue in vite config

[Alice39s]

Updated Vite configuration to properly handle .vue files from @nolebase/ui. Fixed "Unknown file extension '.vue'" error during Vitepress build process.

Add the following line to the optimizeDeps.exclude / ssr.noExternal section in the Vite config:

'@nolebase/ui'.

The build error example:

build error:
Unknown file extension ".vue" for /vercel/path0/node_modules/@nolebase/ui/dist/components/NuTag/index.vue
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".vue" for /vercel/path0/node_modules/@nolebase/ui/dist/components/NuTag/index.vue
    at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:160:9)
    at defaultGetFormat (node:internal/modules/esm/get_format:203:36)
    at defaultLoad (node:internal/modules/esm/load:143:22)
    at async ModuleLoader.load (node:internal/modules/esm/loader:553:7)
    at async ModuleLoader.moduleProvider (node:internal/modules/esm/loader:434:45)
error: script "build" exited with code 1
Error: Command "npm run build" exited with 1

[nekomeowww]

Thanks, merged.