Adopt @microbit/eslint-config

Replaces the local flat config with the shared one, moving to ESLint 10
and type-checked linting via the project service. eslint, @eslint/js,
globals and typescript-eslint are no longer individually managed here.

Fixes everything the new rules surfaced rather than carrying overrides:
@ts-ignore in tests becomes described @ts-expect-error, hasOwnProperty
calls go through Object.prototype, bytes read from the hex are typed as
their enums, the import-hex error message joins its filename array
explicitly, a dead runtimeEndAddress computation goes, and the
flash-regions fallback error gains a cause (lib now includes
ES2022.Error).

Author: microbit-matt-hillsdon

eslint.config.mjs

@@ -1,18 +1,13 @@
-import globals from 'globals';
-import pluginJs from '@eslint/js';
-import tseslint from 'typescript-eslint';
+import microbit from '@microbit/eslint-config';
 
-/** @type {import('eslint').Linter.Config[]} */
 export default [
-  { ignores: ['docs', 'coverage', 'dist', 'src/types'] },
-  { files: ['**/*.{js,mjs,cjs,ts}'] },
-  { languageOptions: { globals: { ...globals.browser, ...globals.node } } },
-  pluginJs.configs.recommended,
-  ...tseslint.configs.recommended,
   {
-    rules: {
-      '@typescript-eslint/ban-ts-comment': 'off',
-      'no-prototype-builtins': 'off',
-    },
+    ignores: [
+      // Typedoc output.
+      'docs',
+      // Not part of any tsconfig project.
+      'vitest.config.mts',
+    ],
   },
+  ...microbit,
 ];