feat(runtime-tests): integration test suite

21 test files covering components, composables, focus, lifecycle,
and scheduler through the public render() API.

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

packages/runtime-tests/vite.config.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from "vite-plus";
+import vueJsx from "@vitejs/plugin-vue-jsx";
+
+export default defineConfig({
+  plugins: [vueJsx()],
+  lint: {
+    options: { typeAware: true, typeCheck: true },
+  },
+  fmt: {},
+});