Fix CommonJS package entrypoint

[jamilahmadzai]

Fixes #11.

Summary

• point the package main field at the CommonJS file produced by the existing build
• point the CommonJS exports["."].require target at the same built file
• keep the ESM import and types entries unchanged

Validation

• corepack pnpm install --frozen-lockfile --ignore-scripts
• corepack pnpm run build
• node -e "const plugin = require('.'); console.log(Object.keys(plugin)); console.log(typeof (plugin.default || plugin.optimizeCssModules));"
• npm pack --dry-run --ignore-scripts --json .
• git diff --check

[simonwep]

Valid, but I do not endorse this practice of "microbounties" where everything from front-to-end is AI generated just for the sake of collecting contributions. It's just a lot of noise. Next time you'll be blocked.