fix: resolve next/font/local loading issues

[Chiman2937]

Hi, @valentinpalkovic !

I've applied the same fix from #32998 to the Vite plugin and discovered additional bugs that needed to be addressed.

Summary

This PR fixes two critical bugs that prevented local fonts from loading correctly in development mode with next/font/local.

Changes

1. Fix: Support top-level weight/style in next/font/local with string src

• same with #32298

2. Fix @fs URL formatting and CSS syntax in @font-face (new bug) ✨

Commit: fix: add slash separator and semicolon in @font-face CSS

Issues Fixed:

• Missing slash between @fs prefix and font path

  • Before: /@fsC:/path/to/font.woff2 → 404 error
  • After: /@fs/C:/path/to/font.woff2 → 200 (works correctly)

• Missing semicolon after src property in @font-face rule

  • This caused CSS parsing errors, preventing font requests entirely

Files Changed:

• src/plugins/next-font/local/get-font-face-declarations.ts

Before:

  @font-face {
    font-family: font-5c0ab9;
    // ❌ missing / after @fs
    // ❌ missing ; after src value
    src: url(/@fsC:/git/WeGo/WeGo/src/assets/fonts/PretendardVariable.woff2)
    font-weight: 45 920;
  }

After:

  @font-face {
    font-family: font-5c0ab9;
    src: url(/@fs/C:/git/WeGo/WeGo/src/assets/fonts/PretendardVariable.woff2);
    font-weight: 45 920;
  }

Test Result for second issue

💡 1. load font with next font local like under:

export const pretendard = localFont({
  src: [{ path: '../assets/fonts/PretendardVariable.woff2', weight: '45 920' }],
  variable: '--font-pretendard',
  display: 'swap',
});

❌ before add / after @fs

✅ after add / after @fs

💡 2. load font with next font local like under:

export const pretendard = localFont({
  src: '../assets/fonts/PretendardVariable.woff2', //variable font
  variable: '--font-primary',
  display: 'swap',
  weight: '45 920', //variable weight
});

❌ before add ; after src value & add / after @fs

no request for font / because of invalid css (missing ;)

✅ after add ; after src value & add / after @fs