test: split vitest into unit and gateway

vitest.unit.config.ts

@@ -0,0 +1,20 @@
+import { defineConfig, mergeConfig } from "vitest/config";
+import baseConfig from "./vitest.config.ts";
+
+const baseTest = (baseConfig as { test?: { include?: string[]; exclude?: string[] } }).test ?? {};
+const include = baseTest.include ?? [
+  "src/**/*.test.ts",
+  "extensions/**/*.test.ts",
+  "test/format-error.test.ts",
+];
+const exclude = baseTest.exclude ?? [];
+
+export default mergeConfig(
+  baseConfig,
+  defineConfig({
+    test: {
+      include,
+      exclude: [...exclude, "src/gateway/**", "extensions/**"],
+    },
+  }),
+);