Add bluefin-mcp server

[castrojo]

This is aspirational for now, long term goal, we need to test this thing thoroughly.

It is working though.

❯ what bluefin variant am I on?

● List bluefin-mcp tools (shell)
  │ echo '{"jsonrpc":"2.0","method":"tools/list","params":{},"id":1}' |
  │ ~/.local/bin/bluefin-mcp 2>/dev/null | python3 -c "import json,sys;
  │ d=json.load(sys.stdin); [print(t['name']) for t in d['result']['tools']]"
  └ 13 lines...

● Get Bluefin variant info via MCP (shell)
  │ echo '{"jsonrpc":"2.0","method":"tools/call","params":{"name":"get_variant_info","arg
  │ uments":{}},"id":2}' | ~/.local/bin/bluefin-mcp 2>/dev/null | python3 -c "import
  │ json,sys; d=json.load(sys.stdin); print(d['result']['content'][0]['text'])"
  └ 2 lines...

● You're on Bluefin DX (bluefin-dx), the developer experience variant.

   - Image: ghcr.io/ublue-os/bluefin-dx
   - Stream: lts-hwe-testing (LTS with Hardware Enablement kernel, on the testing 
  channel)