We should introduce a Cobra-powered CLI for the otp-api application to allow users to interact with the OTP library and server via command-line and an optional interactive shell (REPL-like mode).

This will make the tool more flexible, allowing users to:

• 🛠️ Generate or validate TOTP/HOTP/OCRA directly from terminal
• ⚙️ Configure parameters (algorithm, digits, period, etc.)
• 🚀 Start or stop the HTTP API server
• 🧪 Run quick test commands interactively (REPL)

📌 Proposed CLI Structure:

otp-cli generate totp     # Generate TOTP
otp-cli generate hotp     # Generate HOTP
otp-cli generate ocra     # Generate OCRA
otp-cli validate totp     # Validate TOTP
otp-cli validate hotp     # Validate HOTP
otp-cli validate ocra     # Validate OCRA
otp-cli server start      # Start the HTTP API server
otp-cli shell             # Start interactive shell (REPL)

✅ Why?

• Improve developer ergonomics
• Useful for quick debugging, testing, and scripting
• CLI is a great companion to the API server
• Interactive mode can serve as a teaching tool or live demo utility

🧩 Tasks:

• Setup spf13/cobra
• Add generate and validate subcommands
• Add server start command to run API
• Add interactive shell with basic command auto-complete
• Add CLI flags for custom configuration