chore(core-realtime): scaffold package

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

packages/core-realtime/vitest.config.ts

@@ -0,0 +1,9 @@
+import path from "node:path";
+import { mergeConfig } from "vitest/config";
+import { nodeVitestConfig } from "@repo/core-typescript/vitest.base.node";
+
+export default mergeConfig(nodeVitestConfig, {
+  resolve: {
+    alias: { "@": path.resolve(__dirname, "./src") },
+  },
+});