chore: migrate MCP servers to mcp SDK 2.0 (FastMCP removed)

[ShotaroKataoka]

Summary

mcp 2.0.0 removes mcp.server.fastmcp — both servers fail at import time:

File "servers/local/server.py", line 31
    from mcp.server.fastmcp import FastMCP
ModuleNotFoundError: No module named 'mcp.server.fastmcp'

In 2.0 the server API lives in mcp.server.mcpserver (MCPServer), and the
old FastMCP class is gone (mcp.server now exposes mcpserver, lowlevel,
apps, ... — no fastmcp). This is not a drop-in bump; it needs a migration.

Dependabot PRs #295 (servers/local range widening to <3) and #297
(servers/remote mcp==2.0.0) were closed with this evidence. The <2 upper
bound in both pyproject.toml files stays until this issue is done.

Verified locally: uv pip install mcp[cli]==2.0.0 into the servers/local venv →
import server fails as above. With mcp 1.28/1.29 everything is green.

Scope

• servers/local/server.py (+ server_acp.py if it touches mcp server APIs)
• servers/remote/server.py
• Both pyproject.toml bounds + servers/remote/constraints.txt (make lock)
• Check the FastMCP-specific surface we use: mcp.tool() registration,
  instructions, streamable-HTTP transport wiring in remote, stdio in local

Migration reference

• SDK v2 migration guide: https://github.com/modelcontextprotocol/python-sdk (2.0 release notes)
• New entry point: mcp.server.mcpserver.MCPServer

Acceptance

• Both servers start and register all contract tools on mcp 2.x
• make test green; local stdio smoke test + remote container-deps resolve
• Dependabot upper bound relaxed to <3