Remove leftover Webpack references across the codebase and docs following the esbuild/Vite migration (<mention class="mention" data-id="64605" data-type="work_package" data-text="#OP-17301" data-display-id="OP-17301">#OP-17301</mention> ):

* Replace Webpack-specific type declarations with own global types

* Remove unsupported Webpack magic comments

* Update stale Webpack references in documentation and code comments

* Delete dead Webpack build, test, and tooling scripts

* Drop obsolete Webpack linting configuration Begin of the insertion


### Hints for QA

Dev-facing so no QA pass needed.End of the insertion