fix: support Angular CLI 21.2.x findUpSync rename

In Angular CLI 21.2, the synchronous findUp utility was renamed to
findUpSync, making the old findUp async. Importing findUp statically
then passing its return value (now a Promise) as a file path caused:

  "The "path" argument must be of type string or an instance of Buffer
  or URL. Received an instance of Promise."

Replace the static import with a runtime require that prefers findUpSync
(21.2+) and falls back to findUp (≤21.1), keeping compatibility across
both CLI ranges without breaking existing behaviour.

Author: arturovt

libs/single-spa-community-angular/webpack/index.ts

@@ -1,5 +1,10 @@
 import * as fs from 'fs';
-import { findUp } from '@angular/cli/src/utilities/find-up';
+
+// Angular CLI 21.2+ renamed the sync variant to `findUpSync`; ≤21.1 only exports `findUp` (sync).
+// We load both at runtime and prefer `findUpSync` so the code works across both ranges.
+// eslint-disable-next-line @typescript-eslint/no-require-imports
+const { findUpSync: _findUpSync, findUp: _findUp } = require('@angular/cli/src/utilities/find-up');
+const findUp: (names: string | string[], from: string) => string | null = _findUpSync ?? _findUp;
 
 import { externals } from './externals';
 import { removeMiniCssExtractRules } from './webpack-5/remove-mini-css-extract';