fix: resolve Windows SCSS import failures in dev server

On Windows, Next.js's bundled sass-loader fails to resolve SCSS imports
from node_modules due to path resolution issues with resolve-url-loader
and the legacy sass API.

This patch to next@16.2.3's compiled sass-loader makes three changes:
1. Forces modern-compiler API instead of legacy, enabling loadPaths support
2. Disables webpackImporter (defaults to false) so sass uses its own
   native resolver instead of webpack's, which loses path context on Windows
3. Adds node_modules to loadPaths so package-style @import statements
   like @primer/css and @primer/primitives resolve correctly

Also adds loadPaths to sassOptions in next.config.ts as the proper
configuration surface for this fix.

Fixes dev server startup on Windows (native, no WSL required).
Tested on Windows 11 with Node.js 24.

Author: anarefolio

next.config.ts

@@ -37,6 +37,11 @@ const config: NextConfig = {
   sassOptions: {
     quietDeps: true,
     silenceDeprecations: ['legacy-js-api', 'import', 'global-builtin', 'color-4-api'],
+    loadPaths: [
+      path.join(process.cwd(), 'node_modules'),
+      path.join(process.cwd(), 'node_modules/@primer/css/node_modules'),
+      process.cwd(),
+    ],
   },
   // Don't use automatic Next.js logging in dev unless the log level is `debug` or higher
   // See `src/observability/logger/README.md` for log levels