feat(core): add vitest config and constants

packages/core/src/config.ts

@@ -0,0 +1 @@
+export const SESSION_COOKIE = "session";

packages/core/vitest.config.ts

@@ -0,0 +1,17 @@
+import { defineConfig } from "vitest/config";
+import { fileURLToPath, URL } from "node:url";
+
+export default defineConfig({
+  test: {
+    globals: true,
+    coverage: {
+      provider: "v8",
+      reportsDirectory: "./tests/coverage",
+    },
+  },
+  resolve: {
+    alias: {
+      "@": fileURLToPath(new URL("./src", import.meta.url)),
+    },
+  },
+});