Implement secure clone-demo.sh script with comprehensive safety measures

[Copilot]

This PR addresses critical security vulnerabilities by implementing a safe demo cloning script with comprehensive protection against dangerous directory removal operations.

Overview

The clone-demo.sh script provides a secure way to clone and set up onchain testkit demo projects while preventing catastrophic system damage from potentially dangerous rm -rf commands.

Key Features

Enhanced Portability

• Uses #!/usr/bin/env bash shebang for cross-platform compatibility
• Supports both npm and yarn package managers
• Strict error handling with set -euo pipefail

Critical Safety Validation

The script implements multiple layers of protection against dangerous directory operations:

# These operations are safely blocked
./clone-demo.sh -d "/"        # ERROR: Refusing to remove dangerous directory
./clone-demo.sh -d "/home"    # ERROR: Refusing to remove dangerous directory
./clone-demo.sh -d ""         # ERROR: Directory path cannot be empty

Comprehensive Protection

• System Directory Protection: Blocks removal of critical paths (/, /home, /usr, /bin, /sbin, /etc, /var, /boot, /root, /sys, /proc, /dev, /lib, /lib64, /opt, /mnt, /media, $HOME)
• Path Normalization: Resolves relative paths and validates both original and absolute paths
• Interactive Confirmation: Shows both relative and absolute paths before removal operations
• Input Validation: Prevents empty, whitespace-only, or dangerously short paths

Usage Examples

# Clone the default demo repository
./clone-demo.sh

# Clone with custom directory name
./clone-demo.sh -d my-demo-project

# Clean existing directory and clone (with confirmation)
./clone-demo.sh --clean

# Force clean without prompts (still blocks dangerous paths)
./clone-demo.sh --clean --force

# Clone a specific repository
./clone-demo.sh https://github.com/user/specific-repo.git

# Show all available options
./clone-demo.sh --help

Additional Features

• Colored Output: User-friendly colored messages for info, warnings, errors, and success
• Flexible Options: Custom directory names, repository URLs, setup control
• Error Handling: Graceful error handling with descriptive messages
• Signal Trapping: Handles script interruption safely
• Comprehensive Documentation: Built-in help system and README integration

The script maintains all existing functionality while providing robust security measures that prevent accidental system damage, making it safe for developers to use in various environments.

Fixes #15.

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[joe10832]

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