fix(a2a): export package entrypoint (#124)

Author: miyaontherelay

packages/a2a/package.json

@@ -4,6 +4,13 @@
   "type": "module",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js",
+      "default": "./dist/index.js"
+    }
+  },
   "scripts": {
     "build": "rm -rf dist tsconfig.tsbuildinfo && tsc",
     "test": "vitest run --passWithNoTests",