feat: add streamable-http transport via MCP_TRANSPORT env

[terafin]

Summary

Adds streamable-http transport (and SSE) via the MCP_TRANSPORT env var, gated so existing stdio users are unaffected. Enables deployment behind an MCP gateway (bifrost, mcp-proxy, etc.) as a remote MCP without an stdio-over-HTTP wrapper like supergateway.

MCP_TRANSPORT=stdio           (default) — original behavior, unchanged
MCP_TRANSPORT=streamable-http — HTTP on MCP_HOST:MCP_PORT (path /mcp)
MCP_TRANSPORT=sse             — SSE on MCP_HOST:MCP_PORT

Additional changes

• Bumps dependency floor to mcp>=1.8.0 (where streamable-http landed in the SDK).
• Folds server.py's __main__ block into main.py so both entry points behave identically — single launch surface regardless of how the package is invoked.
• Adds a Dockerfile defaulting to MCP_TRANSPORT=streamable-http on 0.0.0.0:8000 for drop-in remote deployment.

Test plan

• MCP_TRANSPORT=stdio (default) unchanged — existing Claude Desktop / stdio configs keep working.
• MCP_TRANSPORT=streamable-http binds 0.0.0.0:8000 and answers /mcp per FastMCP defaults.
• MCP_TRANSPORT=sse binds the SSE endpoint per FastMCP defaults.
• Image runs as drop-in remote MCP behind bifrost — validated live for ~24h with no regressions.

Backwards compatibility

Zero behavior change at default config. MCP_TRANSPORT defaults to stdio — existing stdio users (Claude Desktop, MCP CLI, etc.) see no difference. The new transports are strictly additive.

Design notes

• Env var (not CLI flag) chosen because the typical remote-MCP deployment pattern is container-based, where env vars are the natural config surface.
• Default port 8000 chosen to align with FastMCP's documented examples.
• Names follow FastMCP's transport name conventions exactly (stdio / streamable-http / sse) — no new vocabulary.

🤖 Generated with Claude Code