Add initial Stinger release

[0x4D31]

Summary

• publish Stinger as a clean initial open-source release for macOS and Linux
• include Watch Mode with FIFO, regular-file, socket, local-service, and optional fanotify traps
• include Protected Sessions with a fake HOME, reduced environment, credential-command tripwires, and scoped response
• include focused installation, configuration, sandboxing, security, contribution, and release documentation

Validation

• gofmt clean
• go mod tidy -diff clean
• go vet ./...
• staticcheck ./...
• Linux and macOS cross-builds for amd64 and arm64
• govulncheck ./... — no vulnerabilities found
• GitHub Actions — Linux/macOS tests, Linux race tests, doctor self-tests, and fanotify integration all passed