chore(build): replace npm with rnr task runner

[CalvinAllen]

Summary

• Remove Node.js dependencies (husky, commitlint) for local development
• Replace npm scripts with rnr task runner
• Add platform binaries for all 5 supported platforms
• Update documentation (CLAUDE.md, README.md)

Changes

Removed:

• .husky/commit-msg - Local commit linting (CI still validates)
• package.json / package-lock.json - No longer needed
• node_modules/ dependency

Added:

• .rnr/ - Platform binaries and config
• rnr / rnr.cmd - Cross-platform wrapper scripts
• rnr.yaml - Task definitions

Available Tasks

./rnr --list         # List all tasks
./rnr check          # Format, lint, test
./rnr build          # Build CLI and shim
./rnr test           # Run tests
./rnr deploy-local   # Build and deploy (Windows)

Test plan

• Clone fresh and run ./rnr check
• Verify ./rnr build produces binaries
• Verify ./rnr --list shows all tasks