build: update to node 22 and pnpm (#3616)

This commit brings the project to support node 22 which became LTS and
fixes broken builds with typescript 5.7+ until vue-tsc is updated and
replaces npm with pnpm.

- Update tsconfig for node 22
- Pin typescript to 5.6.x to not break vue-tsc
- Replace npm with pnpm (corepack recommended)
- Update Makefile and main workflow for pnpm
- Migrate to eslint 9 flat config
- Fix broken imports
- Exclude non-TS vue files for vue-tsc

frontend/src/main.ts

@@ -4,7 +4,7 @@ import VueNumberInput from "@chenfengyuan/vue-number-input";
 import VueLazyload from "vue-lazyload";
 import { createVfm } from "vue-final-modal";
 import Toast, { POSITION, useToast } from "vue-toastification";
-import {
+import type {
   ToastOptions,
   PluginOptions,
 } from "vue-toastification/dist/types/types";