refactor(api): 统一前端API调用使用apiFetch并优化错误处理

refactor: 替换直接fetch调用为apiFetch以统一处理错误和响应
fix(server): 改进QR码验证的错误消息和密码哈希处理

src/api.js

@@ -19,7 +19,12 @@ export async function apiFetch(endpoint, options = {}) {
   })
 
   if (!response.ok) {
-    throw new Error(`API call failed with status: ${response.status}`)
+    // Try to parse the error response body from the server
+    const errorData = await response.json()
+    throw new Error(errorData.message || `API call failed with status: ${response.status}`)
+  }
+  if (response.status === 204) {
+    return null
   }
 
   return response.json()