fix(mcp): remove SSE support; keep stdio default when type is omitted

- Backend: reject "sse" in validators; accept missing type as stdio; require url only for http (mcp.rs, claude_mcp.rs)
- Frontend: McpServer.type narrowed to "stdio" | "http" (optional) (src/types.ts)
- UI: avoid undefined in list item details (McpListItem)
- Claude-only sync after delete to update ~/.claude.json (commands.rs)

Notes:
- Ran typecheck and cargo check: both pass
- Clippy shows advisory warnings unrelated to this change
- Prettier check warns on a few files; limited scope changes kept minimal

src-tauri/src/claude_mcp.rs

@@ -76,16 +76,15 @@ pub fn upsert_mcp_server(id: &str, spec: Value) -> Result<bool, String> {
     if !spec.is_object() {
         return Err("MCP 服务器定义必须为 JSON 对象".into());
     }
-    let t = spec
-        .get("type")
-        .and_then(|x| x.as_str())
-        .unwrap_or("");
-    if t != "stdio" && t != "http" {
-        return Err("MCP 服务器 type 必须是 'stdio' 或 'http'".into());
+    let t_opt = spec.get("type").and_then(|x| x.as_str());
+    let is_stdio = t_opt.map(|t| t == "stdio").unwrap_or(true); // 兼容缺省（按 stdio 处理）
+    let is_http = t_opt.map(|t| t == "http").unwrap_or(false);
+    if !(is_stdio || is_http) {
+        return Err("MCP 服务器 type 必须是 'stdio' 或 'http'（或省略表示 stdio）".into());
     }
 
     // stdio 类型必须有 command
-    if t == "stdio" {
+    if is_stdio {
         let cmd = spec.get("command").and_then(|x| x.as_str()).unwrap_or("");
         if cmd.is_empty() {
             return Err("stdio 类型的 MCP 服务器缺少 command 字段".into());
@@ -93,7 +92,7 @@ pub fn upsert_mcp_server(id: &str, spec: Value) -> Result<bool, String> {
     }
 
     // http 类型必须有 url
-    if t == "http" {
+    if is_http {
         let url = spec.get("url").and_then(|x| x.as_str()).unwrap_or("");
         if url.is_empty() {
             return Err("http 类型的 MCP 服务器缺少 url 字段".into());