[MFA-G]

AI usage

• No AI was used in this PR.
• AI was used: Claude Code + Claude Opus
  • I have carefully reviewed the AI-generated content myself.

Description

With css.splitting: false, CssPostPlugin pushed each chunk's CSS from renderChunk, so style.css followed render order. When a module that imports CSS is shared by several entries, it gets its own chunk, and that chunk's CSS was appended after the entry's own CSS even though the entry imports it first.

This PR stores each chunk's CSS under its preliminary file name in renderChunk, then merges in generateBundle by walking the entry chunks the way Vite does for cssCodeSplit: false: a chunk's static imports come first, then the chunk itself, and dynamically imported chunks are added last.

Two tests are added to tests/css.test.ts, the repro from the issue and a case with a dynamic import. Both fail on main and pass with this change. pnpm test run, pnpm lint and pnpm typecheck all pass.

Linked Issues

fixes #1086

Additional context

The splitting: true path is unchanged.

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