feat(mcp): enhance MCP transport support and add server management UI

- Extend McpTransport to support "sse" in schemas.
- Refactor McpToolClient to handle both "streamable_http" and "sse" transports.
- Introduce McpServerDialog for managing MCP server configurations, including transport settings and tool synchronization.
- Replace McpServersSection with the new dialog component for improved server management.
- Add tests for MCP transport handling and server dialog functionality.

backend/tests/test_mcp_client.py

@@ -0,0 +1,51 @@
+import unittest
+from contextlib import asynccontextmanager
+from unittest.mock import patch
+
+from models import RuntimeMcpServer
+from schemas import McpServerUpsert
+from services.tools.mcp_client import McpToolClient
+
+
+class McpTransportTests(unittest.IsolatedAsyncioTestCase):
+    def test_server_schema_accepts_sse(self):
+        server = McpServerUpsert(
+            name="旧版 MCP 服务",
+            transport="sse",
+            url="https://mcp.example.com/sse",
+        )
+
+        self.assertEqual(server.transport, "sse")
+
+    async def test_sse_transport_uses_sdk_sse_client(self):
+        captured: dict = {}
+
+        @asynccontextmanager
+        async def fake_sse_client(url, **kwargs):
+            captured["url"] = url
+            captured.update(kwargs)
+            yield "read-stream", "write-stream"
+
+        server = RuntimeMcpServer(
+            id="mcp_sse",
+            transport="sse",
+            url="https://mcp.example.com/sse",
+        )
+        client = McpToolClient()
+
+        with patch("services.tools.mcp_client.sse_client", fake_sse_client):
+            async with client._transport_streams(
+                server,
+                {"Authorization": "Bearer test"},
+                20,
+            ) as streams:
+                self.assertEqual(streams, ("read-stream", "write-stream"))
+
+        self.assertEqual(captured["url"], server.url)
+        self.assertEqual(captured["headers"], {"Authorization": "Bearer test"})
+        self.assertEqual(captured["timeout"], 20)
+        self.assertEqual(captured["sse_read_timeout"], 20)
+
+
+if __name__ == "__main__":
+    unittest.main()