feat(k3cloud): 新增金蝶云星空 MCP 服务器

新增完整的 K3Cloud MCP 服务器实现，包含配置管理、API 客户端、工具定义和签名验证
更新文件工具 MCP 服务器的 MinIO 配置和上传路径前缀

k3cloud_mcp/k3cloud_mcp/client.py

@@ -0,0 +1,50 @@
+import json
+from typing import Any, Dict
+
+import requests
+
+from .config import Config
+from .signing import build_headers
+
+
+def build_save_url(path: str) -> str:
+    """Build the Save API URL."""
+    return f"{Config.BASE_URL.rstrip('/')}{path}"
+
+
+def save(formid: str, data_payload: Any, timeout: int = 30) -> Dict[str, Any]:
+    """
+    Call the K3Cloud Save API.
+
+    `data_payload` can be a JSON object or a pre-serialized JSON string.
+    """
+    save_service_path = "/Kingdee.BOS.WebApi.ServicesStub.DynamicFormService.Save.common.kdsvc"
+    normalized_formid = str(formid or "").strip()
+    if not normalized_formid:
+        raise ValueError("formid 不能为空")
+    if data_payload is None:
+        raise ValueError("data_payload 不能为空")
+
+    if isinstance(data_payload, str):
+        payload_value = data_payload.strip()
+        if not payload_value:
+            raise ValueError("data_payload 不能为空字符串")
+    else:
+        try:
+            payload_value = json.dumps(data_payload, ensure_ascii=False)
+        except TypeError as exc:
+            raise TypeError("data_payload 必须是可序列化的 JSON 对象或 JSON 字符串") from exc
+
+    payload = {
+        "formid": normalized_formid,
+        "data": payload_value,
+    }
+
+    response = requests.post(
+        build_save_url(save_service_path),
+        json=payload,
+        headers=build_headers(save_service_path),
+        timeout=timeout,
+    )
+    response.raise_for_status()
+    return response.json()