Empty css issue

[owjs3901]

Create css file if css is empty

Some bundler check existing file before read css file.

So, Even if css is empty, plugin should create css file.

[changeset-bot]

🦋 Changeset detected

Latest commit: acb5eb0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 4 packages

Name	Type
@devup-ui/rsbuild-plugin	Patch
@devup-ui/webpack-plugin	Patch
@devup-ui/vite-plugin	Patch
@devup-ui/next-plugin	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Files with missing lines	Coverage Δ
libs/extractor/src/lib.rs	96.77% <ø> (ø)
packages/rsbuild-plugin/src/plugin.ts	100.00% <100.00%> (ø)
packages/vite-plugin/src/plugin.ts	100.00% <100.00%> (ø)
packages/webpack-plugin/src/loader.ts	100.00% <100.00%> (ø)

... and 3 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.