Fix rollup errors

[sparr]

On a fresh clone of this repo, rollup -c fails with errors related to ES/CJS problems.

(node:1224971) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///home/sparr/src/games/Screeps/codebases/2025/rollup.config.js is not specified and it doesn't parse as CommonJS.
Reparsing as ES module because module syntax was detected. This incurs a performance overhead.
To eliminate this warning, add "type": "module" to /home/sparr/src/games/Screeps/codebases/2025/package.json.

And then there are further errors that I failed to capture, related to the use of require.

This PR updates the package.json and replaces require in the rollup config.