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/components/mcp/useMcpValidation.ts

@@ -41,7 +41,10 @@ export function useMcpValidation() {
         if (server.type === "stdio" && !server.command?.trim()) {
           return t("mcp.error.commandRequired");
         }
-        if (server.type === "http" && !server.url?.trim()) {
+        if (
+          (server.type === "http" || server.type === "sse") &&
+          !server.url?.trim()
+        ) {
           return t("mcp.wizard.urlRequired");
         }
       } catch (e: any) {
@@ -73,7 +76,10 @@ export function useMcpValidation() {
           if (typ === "stdio" && !(obj as any)?.command?.trim()) {
             return t("mcp.error.commandRequired");
           }
-          if (typ === "http" && !(obj as any)?.url?.trim()) {
+          if (
+            (typ === "http" || typ === "sse") &&
+            !(obj as any)?.url?.trim()
+          ) {
             return t("mcp.wizard.urlRequired");
           }
         }