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/i18n/locales/zh.json

@@ -483,6 +483,7 @@
       "type": "类型",
       "typeStdio": "stdio",
       "typeHttp": "http",
+      "typeSse": "sse",
       "command": "命令",
       "commandPlaceholder": "npx 或 uvx",
       "args": "参数",