Undo the test-suite workarounds for the broken manifests

With the manifests broken, b65f265 and 4539abb worked around the symptoms:
rootJs imported itself by relative path instead of as @pezkuwi/dev, a
hand-written dynamic.d.mts stood in for the .mjs, and suite.spec.ts declared
its own describe/it/expect and imported a .d.ts at run time, which failed
the file. All three are reverted to upstream's form.

The import-attribute check now expects `with`: Node 22 removed `assert`.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

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

@@ -1,4 +0,0 @@
-// 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 './testJson.json' with { 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';
@@ -20,7 +20,7 @@ export function bigIntExp (): bigint {
 export async function dynamic (a: number, b: number): Promise<number> {
   // NOTE we go via this path so it points to the same location in both ESM
   // and CJS output (a './dynamic' import would be different otherwise)
-  const { sum } = await import('./dynamic.mjs');
+  const { sum } = await import('@pezkuwi/dev/rootJs/dynamic.mjs');
 
   // eslint-disable-next-line @typescript-eslint/no-unsafe-return
   return sum(a, b);