Migrate all JS config and tools to TS and fix a number of type issues.
This required Node.js 22.18.0 or greater where [type-stripping was
enabled](https://nodejs.org/en/blog/release/v22.18.0) by default.
Given that Node 22 is the current LTS, I think it's ok to assume that
the user has a recent version of it.
Webpack currently requires the `--disable-interpret` flag to work,
should be fixed eventually with
https://github.com/webpack/webpack-cli/issues/4525.
`fast-glob` is replaced by `fs.globSync`, available in Node 22.0.0 or
greater.
Adds types to various low-level modules. All changes are type-only, no
runtime changes. `tsc` now reports 38 less errors.
One problem was that `@types/sortablejs` does not accept promise return
in its functions which triggered the linter, so I disabled the rules on
those line.
None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).
`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.
Everything appears to work fine.
silverwind