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" }
}

tests/hooks/useMcpValidation.test.tsx

@@ -87,6 +87,15 @@ describe("useMcpValidation", () => {
       expect(validateTomlConfig("foo")).toBe("mcp.wizard.urlRequired");
     });
 
+    it("returns url required when sse server missing url", () => {
+      tomlToMcpServerMock.mockReturnValue({
+        type: "sse",
+        url: "",
+      });
+      const { validateTomlConfig } = getHookResult();
+      expect(validateTomlConfig("foo")).toBe("mcp.wizard.urlRequired");
+    });
+
     it("surface tomlToMcpServer errors via formatter", () => {
       tomlToMcpServerMock.mockImplementation(() => {
         throw new Error("normalize failed");
@@ -128,6 +137,11 @@ describe("useMcpValidation", () => {
       expect(validateJsonConfig('{"type":"http","url":""}')).toBe("mcp.wizard.urlRequired");
     });
 
+    it("requires url for sse type", () => {
+      const { validateJsonConfig } = getHookResult();
+      expect(validateJsonConfig('{"type":"sse","url":""}')).toBe("mcp.wizard.urlRequired");
+    });
+
     it("returns empty string when json config valid", () => {
       const { validateJsonConfig } = getHookResult();
       expect(
@@ -142,4 +156,3 @@ describe("useMcpValidation", () => {
     });
   });
 });
-