[REFACTOR] Remove SSE transport support

[jja6312]

Summary
Removes SSE from the transport options in MCP Server.

Motivation
SSE, a deprecated transport option, will be replaced by the STREAMABLE HTTP option already in the current project, which follows the latest official documentation guidance for current projects without specific requirements.

Proposal

• Keep only stdio and streamable-http as officially supported transports

**Additional context
The following documentation from fastmcp confirms that sse has been deprecated and that the existing streamable-http is sufficiently functional

• "The Server-Sent Events transport is maintained for backward compatibility but is superseded by Streamable HTTP for new deployments."
• "Use Streamable HTTP for new deployments unless you have specific infrastructure requirements for SSE." (Use streamable HTTP for new deployments unless you have specific infrastructure requirements for SSE.)

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Summary
MCP Server의 transport 옵션 중, SSE를 제거합니다.

Motivation
deprecated transport 옵션인 sse는 현재 프로젝트에 이미 있는 streamable http 옵션이 대체하며, 특정 요구사항이 없는 현재 프로젝트에서는 최신 공식문서 가이드를 따릅니다.

Proposal

• 공식 지원하는 transport는 stdio와 streamable-http만 유지

Additional context
fastmcp의 아래 문서 내용에 따르면 sse deprecated 사실 및 기존 streamable http로 충분히 동작 가능함을 확인할 수 있습니다

• "Server-Sent Events transport is maintained for backward compatibility but is superseded by Streamable HTTP for new deployments."(이전 버전과의 호환성을 위해 유지되지만 새 배포에서는 streamable HTTP로 대체)
• "Use Streamable HTTP for new deployments unless you have specific infrastructure requirements for SSE."(SSE에 대한 특정 인프라 요구 사항이 없는 한 새 배포에는 streamable HTTP를 사용하세요.)