fix(test): isolate jsdom storage on Node 26

scripts/vitest-environment.compat.spec.ts

@@ -0,0 +1,14 @@
+// @vitest-environment jsdom
+import { describe, expect, it } from 'vitest'
+
+describe('Vitest jsdom compatibility', () => {
+  it('provides isolated browser storage instead of Node process storage', () => {
+    if (process.allowedNodeEnvironmentFlags.has('--webstorage')) {
+      expect(process.execArgv.filter(argument => argument === '--no-webstorage')).toHaveLength(1)
+    }
+    localStorage.setItem('dsh-vitest-storage-probe', 'available')
+
+    expect(localStorage.getItem('dsh-vitest-storage-probe')).toBe('available')
+    localStorage.removeItem('dsh-vitest-storage-probe')
+  })
+})