Add Dockerfile for MCP server (Glama evaluation)

[aleksUIX]

Adds a Dockerfile that builds and runs rtblint-mcp, so Glama can start the server and pass its introspection check (which assigns the quality score referenced by the awesome-list badge).

Multi-stage: builds rtblint-mcp release, runs it on debian:bookworm-slim. The server speaks MCP over stdio, so the container entrypoint is just the binary.

Verified locally: builds clean, and the binary answers initialize (returns serverInfo) and tools/list (validate_bid_request, validate_bid_response, list_openrtb_versions) over stdio.

[aleksUIX]

Superseded by the Smithery deployment commit on main (a057f64), which already adds a root Dockerfile building rtblint-mcp (plus smithery.yaml). That Dockerfile is functionally equivalent to this one and better scoped (copies only manifests + crates), so this PR is redundant. Closing.