Add CLAUDE.md with project-specific rules (test structure, naming
conventions, MCP tools reference). Add .mcp.json for rust-mcp and
crates-io MCP servers. Add rust-toolchain.toml pinning stable with
rustfmt and clippy. Add .claude/settings.json with PostToolUse hook
that runs cargo test automatically after every file edit.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
