Fix TypeScript type definitions for test suite

- Add explicit Describe and It interfaces with todo support
- Fix mock type compatibility in jest.ts
- Update import assertions to import attributes (assert -> with)
- Add dynamic.d.mts declaration file
- Fix spec files to use explicit type declarations

packages/dev/src/rootJs/dynamic.d.mts

@@ -0,0 +1,4 @@
+// Copyright 2017-2026 @pezkuwi/dev authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+export function sum(a: number, b: number): number;

packages/dev/src/rootJs/index.ts

@@ -5,7 +5,7 @@
 import './augmented.js';
 
 /** This import should appear as-in in the ouput (cjs without asserts) */
-import testJson from '@pezkuwi/dev/rootJs/testJson.json' assert { type: 'json' };
+import testJson from '@pezkuwi/dev/rootJs/testJson.json' with { type: 'json' };
 
 /** Double double work, i.e. re-exports */
 export { Clazz } from './Clazz.js';