test: Remove non-configurable window.location stub

sinon cannot stub window.location in modern browsers as it is non-configurable
and non-writable. The stub was a leftover from before the Navigation API refactor
— location.assign/replace are no longer used in the router or tests.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sbesh91

test/router.test.js

@@ -40,6 +40,10 @@ describe('Router', () => {
 		document.body.appendChild(scratch);
 		history.replaceState(null, null, '/');
 	});
+	
+	afterEach(() => {
+	  sinon.restore();
+	});
 
 
 	it('should throw a clear error if the LocationProvider is missing', () => {