refactor(rolldown): migrate codemirror to modern-monaco

[webfansplz]

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[Copilot]

Pull request overview

This PR migrates the Rolldown DevTools code viewer/diff viewer from CodeMirror 5 to modern-monaco, updating both dependencies and the UI implementation to use Monaco editors with custom theming and scrollbar styling.

Changes:

• Replace CodeMirror-based viewer/diff components with Monaco equivalents and introduce a new Monaco composable.
• Update styles to target Monaco editor DOM and align scrollbars with app styling.
• Remove CodeMirror dependencies/types and add modern-monaco to workspace/package deps (plus lockfile updates).

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pnpm-workspace.yaml	Removes CodeMirror entries from catalogs; adds modern-monaco.
pnpm-lock.yaml	Reflects dependency swap to modern-monaco and related lock updates.
packages/rolldown/src/uno.config.ts	Minor formatting cleanup.
packages/rolldown/src/nuxt.config.ts	Updates optimizeDeps.include to preload modern-monaco instead of CodeMirror modules.
packages/rolldown/src/app/styles/global.css	Adds app scrollbar CSS vars and Monaco scrollbar styling overrides.
packages/rolldown/src/app/styles/cm.css	Repurposes editor styling from CodeMirror to Monaco while keeping shared font vars.
packages/rolldown/src/app/composables/monaco.ts	New shared Monaco initialization, theme application, editor factory, language guessing, and scroll sync helpers.
packages/rolldown/src/app/composables/codemirror.ts	Removes CodeMirror composable.
packages/rolldown/src/app/components/code/Viewer.vue	Reimplements the code viewer using a read-only Monaco editor with auto-height.
packages/rolldown/src/app/components/code/DiffEditor.vue	Reimplements the diff viewer using two Monaco editors + decoration-based diff highlighting + scroll sync.
packages/rolldown/package.json	Drops CodeMirror deps/types and adds modern-monaco.

Files not reviewed (1)

• pnpm-lock.yaml: Language not supported

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npm i https://pkg.pr.new/@vitejs/devtools@185

npm i https://pkg.pr.new/@vitejs/devtools-kit@185

npm i https://pkg.pr.new/@vitejs/devtools-rolldown@185

npm i https://pkg.pr.new/@vitejs/devtools-rpc@185

commit: 7a6f541

[antfu]

Awesome! Thank you!