refactor: 降级到 Prisma 6，移除 adapter 依赖

Prisma 6 内置 SQLite 引擎，无需 adapter、无需编译工具链，
与 no-whatever 项目保持一致的技术方案。

package.json

@@ -9,8 +9,7 @@
     "lint": "eslint"
   },
   "dependencies": {
-    "@prisma/adapter-libsql": "^7.4.1",
-    "@prisma/client": "^7.4.1",
+    "@prisma/client": "^6.19.2",
     "framer-motion": "^12.34.3",
     "lucide-react": "^0.575.0",
     "next": "16.1.6",
@@ -24,7 +23,7 @@
     "@types/react-dom": "^19",
     "eslint": "^9",
     "eslint-config-next": "16.1.6",
-    "prisma": "^7.4.1",
+    "prisma": "^6.19.2",
     "tailwindcss": "^4",
     "typescript": "^5"
   }