test(portal): add Vitest setup and public-form tests

Introduces vitest config, jsdom setup, and first suites covering
FieldRenderer dispatch and useConditionalLogic evaluation.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/portal/tests/setup.ts

@@ -0,0 +1,18 @@
+import { vi } from 'vitest'
+
+// Deterministic idempotency-key generation for useFormDraft tests.
+if (!globalThis.crypto) {
+  ;(globalThis as { crypto: Crypto }).crypto = {
+    randomUUID: () => '00000000-0000-4000-8000-000000000000',
+    getRandomValues: (buf: Uint8Array) => {
+      for (let i = 0; i < buf.length; i++) buf[i] = 0
+      return buf
+    },
+  } as unknown as Crypto
+}
+
+// Suppress Vue-router usage in isolated composable tests.
+vi.mock('vue-router', () => ({
+  useRoute: () => ({ params: {}, query: {} }),
+  useRouter: () => ({ push: vi.fn(), replace: vi.fn() }),
+}))