feat: add Rust binary calculator example

[bryan-anthropic]

Summary

• First example of the binary server type — a compiled Rust MCP server packaged as an MCPB
• Based on the official Rust SDK calculator example (rmcp 1.2.0, 2 tools: sum/sub, ~80 LOC)
• Includes Cargo.toml, Dockerfile for Docker-based builds, .mcpbignore to exclude source from the bundle, and README with build/pack/test instructions

Motivation

All existing examples use interpreted runtimes (Node.js, Python/UV). This fills the gap for compiled languages (Rust, Go, C++) where a pre-built binary is packaged directly. The calculator is intentionally minimal — zero API keys, no external dependencies, two tools — so it serves as a clear template.

What's included

File	Purpose
manifest.json	v0.3 manifest with server.type = "binary"
Cargo.toml	Standalone Rust project (edition 2024, rmcp 1.2.0)
src/main.rs	Combined calculator server (~80 LOC)
Dockerfile	Build inside Docker (no local Rust needed)
.mcpbignore	Excludes source, keeps only manifest + binary in bundle
README.md	Build, pack, and test instructions

Test plan

• mcpb pack examples/calculator-rust validates manifest and produces correct bundle (only manifest.json + server/mcp-calculator)
• Binary built and tested end-to-end: initialize, tools/list, sum(3,4)→7, sub(10,3)→7
• yarn lint and yarn test pass (218 tests)
• Successfully tested as installed MCPB in Claude Desktop on macOS ARM64

🤖 Generated with Claude Code