feat(rsc): add customBuildApp option

[hi-ogawa]

(Sorry if anyone got pinged by this PR. It wasn't intended and AI did it 😓)

Summary

This PR adds a customBuildApp option that allows downstream frameworks to skip the default buildApp orchestration and implement their own build order.

Motivation

The RSC plugin currently has a hardcoded build pipeline:

• rsc -> ssr -> rsc -> client -> ssr (5 steps with 2 scan build)

With a new API, it allows taking over build pipeline to match framework's need. For example, following is from No SSR example:

// vite.config.ts
import rsc, { getPluginApi } from '@vitejs/plugin-rsc'

export default defineConfig({
  plugins: [
    rsc({
      entries: {
        rsc: './src/framework/entry.rsc.tsx',
      },
      customBuildApp: true,
    }),
  ],
  builder: {
    sharedPlugins: true,
    sharedConfigBuild: true,
    async buildApp(builder) {
      const { manager } = getPluginApi(builder.config)!

      // Scan
      manager.isScanBuild = true
      builder.environments.rsc!.config.build.write = false
      builder.environments.client!.config.build.write = false
      await builder.build(builder.environments.rsc!)
      await builder.build(builder.environments.client!)
      builder.environments.rsc!.config.build.write = true
      builder.environments.client!.config.build.write = true
      manager.isScanBuild = false
      manager.stabilize()

      // Build
      await builder.build(builder.environments.rsc!)
      await builder.build(builder.environments.client!)

      // write manifest
      manager.writeAssetsManifest(['rsc'])
    },
  },
})

---

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commit: fd861a5

[silvenon]

Pretty cool about this flexibility! Also makes it more transparent.

Btw, looking at this config I'm a little unclear on whether sharedConfigBuild: true implies sharedPlugins: true or not? I thought it did.

[hi-ogawa]

Pretty cool about this flexibility! Also makes it more transparent.

Btw, looking at this config I'm a little unclear on whether sharedConfigBuild: true implies sharedPlugins: true or not? I thought it did.

If I remember correctly, one implies another but forgot which is which, so just went with setting both 😅