fix: 统一签名策略，签名不包含body

根本原因：
- 前端签名生成时包含body
- 后端WebFlux验证时body为空
- 导致签名不匹配，认证失败

修复方案：
- 修改前端signature.ts，签名时不包含body
- 修改测试role-auth-manager.ts，与前端保持一致
- 与后端WebFlux实现保持一致

影响范围：
- 所有需要签名验证的API请求
- Token注入登录测试
- 用户管理相关测试

novalon-manage-web/e2e/role-based-tests/shared/role-auth-manager.ts

@@ -39,7 +39,7 @@ export class RoleAuthManager {
       method.toUpperCase(),
       path,
       '',
-      body || '',
+      '',
       timestamp.toString(),
       nonce
     ].join('\n');

novalon-manage-web/src/utils/signature.ts

@@ -16,7 +16,7 @@ export function generateSignature(
   timestamp: number,
   nonce: string
 ): string {
-  const stringToSign = buildStringToSign(method, path, query, body, timestamp, nonce)
+  const stringToSign = buildStringToSign(method, path, query, '', timestamp, nonce)
   
   const signature = CryptoJS.HmacSHA256(stringToSign, SIGNATURE_SECRET)
   const signatureBase64 = CryptoJS.enc.Base64.stringify(signature)