serve: port serve-web from Vite to Rsbuild

[bpowers]

Fixes #901

Ports src/simlin-serve/web from Vite to Rsbuild, removing the monorepo's second bundler (vite, @vitejs/plugin-react, vite-plugin-wasm, vite-plugin-top-level-await all drop out of the lockfile).

Design notes

• output.assetPrefix: './' preserves Vite's base: './' so the SPA stays relocatable under any mount path (the Rust binary embeds it at /; a proxy can mount it elsewhere).
• The flat distPath layout is load-bearing for that relative prefix, not cosmetic: Rspack builds runtime asset URLs as publicPath + <output-relative path>, resolved against the referencing context's base URL — the document on the main thread, but the worker script's own URL inside the engine's Web Worker. Nesting chunks under static/js/ would make the worker resolve the WASM blob to static/js/static/wasm/.... Putting every chunk at the dist root mirrors the flat assets/ directory Vite emitted, and is documented in the config.
• experiments.asyncWebAssembly (same setup as src/app's rsbuild config) handles @simlin/engine's ESM-integration wasm import natively, replacing both Vite plugins.
• A local globals.d.ts declare module '*.css' replaces the declaration vite/client used to provide (mirrors src/app/globals.d.ts).
• @simlin/engine's webpack-vs-vite bundler-detection branches are untouched — they exist for external consumers of the published package (out of scope per the issue).
• build: no dist-level smoke check that @simlin/diagram CSS (theme.css/reset.css) lands in serve-web bundle #828's proposed smoke check should now be written against this layout (dist/index.*.css at the root rather than dist/assets/index-*.css).

Verification

Beyond the unit/lint/tsc gates, verified against the rebuilt simlin-serve binary in a real browser, since worker/wasm resolution is exactly what unit tests can't see:

• editor renders teacup.xmile; the engine worker spawns and the simulation runs (stock sparkline + full series in the variable-details chart), with zero console errors;
• @simlin/diagram theme tokens and katex CSS both land in the emitted CSS (the rsbuild/rspack tree-shakes reset.css side-effect import out of src/app production CSS bundle #708/build: no dist-level smoke check that @simlin/diagram CSS (theme.css/reset.css) lands in serve-web bundle #828 side-effect contract survived the bundler swap);
• all bundle assets resolve with 200s when dist/ is served from a subpath, confirming the relative-URL property still holds.

Also updates the now-stale Vite references: CI step comments, deploy-tooling comment lists, docs/dev/deploy.md, docs/tech-debt.md, and fixes the stale "React 19 + Vite + Jest" line in src/simlin-serve/CLAUDE.md.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.86%. Comparing base (b92f8d1) to head (b6b9a99).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1009   +/-   ##
=======================================
  Coverage   91.86%   91.86%           
=======================================
  Files         247      247           
  Lines      159159   159159           
=======================================
+ Hits       146207   146210    +3     
+ Misses      12952    12949    -3     

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[claude]

Review: serve: port serve-web from Vite to Rsbuild

Reviewed the bundler swap end-to-end (config, package manifest, tsconfig, index.html, tests, docs, and the rust-embed layout contract).

No blocking issues found. The change is well-scoped and the config comments are thorough:

• assetPrefix: './' + the flat distPath correctly preserves the relative-URL relocatability property (the load-bearing detail called out in the comment, and it matches the sibling constraint in src/engine/src/engine-worker.ts about worker self.location resolution).
• experiments.asyncWebAssembly + the .wasm rule is the same setup src/app/config/rsbuild/shared.config.js uses; it correctly replaces vite-plugin-wasm + vite-plugin-top-level-await for @simlin/engine's ESM-integration wasm import.
• vite/client types are cleanly replaced by globals.d.ts (declare module '*.css'); grep confirms no import.meta.env / import.meta.hot usage in src/simlin-serve/web/src/, so the trimmed type surface is sufficient.
• Removing the inline module script tag from index.html is correct since Rsbuild auto-injects from source.entry.index (mirrors the pattern in src/app/public/index.html).
• Rsbuild's default filename pattern in production, combined with the flat distPath, produces dist/index.<hash>.{js,css} at the root -- consistent with the smoke-check assumption noted for the follow-up.
• CI comment update, deploy-tooling comment lists, docs/dev/deploy.md, and docs/tech-debt.md are all consistently updated; src/simlin-serve/CLAUDE.md's stale "React 19 + Vite + Jest" line is fixed.

The author has manually verified worker/WASM resolution and subpath serving in a real browser -- the failure modes unit tests cannot see.

Overall correctness: correct

The patch should not break existing code or tests. No bugs identified.