Add portable bash script for OAuth authentication

[maximelb]

Summary

Adds lc-oauth.sh - a portable bash script that performs LimaCharlie OAuth authentication and outputs a JWT to stdout.

Features

• Cross-platform compatibility: Works on Linux (Debian, Ubuntu, RHEL, Alpine) and macOS
• Multiple netcat variants: Automatically detects and uses BSD, OpenBSD, GNU, or nmap netcat
• MFA support: Handles both TOTP (authenticator apps) and SMS verification
• Browser auto-open: Tries multiple openers (xdg-open, open, wslview, etc.) with manual fallback
• Clean output: JWT goes to stdout only, all status messages to stderr

Usage

./lc-oauth.sh                    # Authenticate with Google
./lc-oauth.sh -p microsoft       # Authenticate with Microsoft  
./lc-oauth.sh -o abc123-def456   # Get JWT for specific org
./lc-oauth.sh -n                 # Manual browser mode (prints URL)

# Use with curl
JWT=$(./lc-oauth.sh)
curl -H "Authorization: bearer $JWT" https://api.limacharlie.io/v1/...

Dependencies

• curl
• netcat (nc, ncat, or netcat)
• timeout (coreutils) or gtimeout (macOS via Homebrew) or perl

Test plan

• Test on Linux (Debian/Ubuntu)
• Test on macOS
• Test with Google OAuth provider
• Test with Microsoft OAuth provider
• Test MFA flow (if account has 2FA enabled)
• Test --no-browser mode

🤖 Generated with Claude Code