feat(rsc): initial bundledDev support

[nihgwu]

Description

Fixes #1217.

• Use the RSC browser wrapper as the bundledDev client entry and statically include reachable client references.
• Include server-imported CSS and assets in the client bundle and derive the development assets manifest from bundled output.
• Preserve React refresh and ordinary client HMR while avoiding custom HMR state, timers, cache invalidation, and Vite internal APIs.
• Document that server-graph and client-boundary changes require a dev-server restart until Vite exposes an atomic bundledDev rebuild-and-reload operation for plugins.

This includes the build-only generateBundle guard also proposed in #1296 as part of the broader bundledDev integration.

[nihgwu]

I tested this PR against a real application with #1295 applied and Vite 8.1.4. The client appeared to hydrate, but the test uncovered a correctness blocker around SSR CSS.

Evidence:

• Normal dev with JavaScript disabled rendered 42 stylesheet links and the complete styled layout.
• bundledDev rendered zero stylesheet links and only one unrelated inline style.
• With JavaScript enabled, route-specific and server-only CSS was still missing.

The underlying problem is that bundledDev transforms client CSS into JavaScript calling updateStyle, serves only bundled memoryFiles, and does not mount the normal transform middleware. plugin-rsc therefore has no valid transformed stylesheet URL to emit into streamed SSR HTML. Crawling the initial server graph is also insufficient because route-specific CSS can be discovered only during the RSC render.

Restoring source CSS URLs produces 404s. Avoiding the links makes SSR depend on JavaScript and still misses server-only styles. Custom CSS middleware, data URLs, or parsing Vite’s generated JavaScript would reproduce Vite internals and would not be an upstream-ready solution.

This PR should therefore remain blocked and should not close #1217 until Vite exposes a server-side way to obtain servable bundled output URLs for CSS/modules and a safe full-rebuild operation for server-graph changes.

Related Vite core API discussion: vitejs/vite#22991