build: migrate to tsdown

Author: danielroe

build.config.ts

@@ -20,7 +20,7 @@
     "dist"
   ],
   "scripts": {
-    "build": "unbuild",
+    "build": "tsdown",
     "dev": "vitest dev",
     "lint": "eslint .",
     "prepare": "simple-git-hooks",
@@ -45,8 +45,8 @@
     "eslint": "9.37.0",
     "lint-staged": "16.2.3",
     "simple-git-hooks": "2.13.1",
+    "tsdown": "^0.15.6",
     "typescript": "5.9.3",
-    "unbuild": "3.6.1",
     "unstorage": "1.17.1",
     "vite": "7.1.9",
     "vitest": "3.2.4"