feat(mcp): add SSE (Server-Sent Events) transport type support

Add comprehensive support for SSE transport type to MCP server configuration,
enabling real-time streaming connections alongside existing stdio and http types.

Backend Changes:
- Add SSE type validation in mcp.rs validate_server_spec()
- Extend Codex TOML import/export to handle SSE servers
- Update claude_mcp.rs legacy API for backward compatibility
- Unify http/sse handling in json_server_to_toml_table()

Frontend Changes:
- Extend McpServerSpec type definition to include "sse"
- Add SSE radio button to configuration wizard UI
- Update wizard form logic to handle SSE url and headers
- Add SSE validation in McpFormModal submission

Validation & Error Handling:
- Add SSE support in useMcpValidation hook (TOML/JSON)
- Extend tomlUtils normalizeServerConfig for SSE parsing
- Update Zod schemas (common.ts, mcp.ts) with SSE enum
- Add SSE error message mapping in errorUtils

Internationalization:
- Add "typeSse" translations (zh: "sse", en: "sse")

Tests:
- Add SSE validation test cases in useMcpValidation.test.tsx

SSE Configuration Format:
{
  "type": "sse",
  "url": "https://api.example.com/sse",
  "headers": { "Authorization": "Bearer token" }
}

src/utils/errorUtils.ts

@@ -84,6 +84,7 @@ export const translateMcpBackendError = (
   }
   if (
     msg.includes("http 类型的 MCP 服务器缺少 url 字段") ||
+    msg.includes("sse 类型的 MCP 服务器缺少 url 字段") ||
     msg.includes("必须包含 url 字段") ||
     msg === "URL 不能为空"
   ) {

src/utils/tomlUtils.ts

@@ -145,13 +145,13 @@ function normalizeServerConfig(config: any): McpServerSpec {
     }
 
     return server;
-  } else if (type === "http") {
+  } else if (type === "http" || type === "sse") {
     if (!config.url || typeof config.url !== "string") {
-      throw new Error("http 类型的 MCP 服务器必须包含 url 字段");
+      throw new Error(`${type} 类型的 MCP 服务器必须包含 url 字段`);
     }
 
     const server: McpServerSpec = {
-      type: "http",
+      type: type as "http" | "sse",
       url: config.url,
     };
     knownFields.add("type");