Add Configuration Support & Improve CLI Validation

[brandonpollett]

Add Configuration Support & Improve CLI Validation

🎯 What's New

• Extension Configuration: Added support for user-configurable values passed as HTTP headers
• Optional Tool Addition: Made tool addition optional in generate command
• Schema-Based Validation: Unified validation using JSON schemas instead of manual functions
• Flexible Headers: Allow uppercase letters in configuration header names

🔧 Key Changes

• Configuration Prompting: New promptExtensionConfiguration() with label/description/header fields
• Generate Command: Updated to prompt for tool addition vs forcing it, with smart success messages
• Init Command: Added Step 3 for configuration setup during project initialization
• Validation Overhaul: Replaced manual validation with validateFieldValue() schema calls
• Header Pattern: Updated from ^x-dre-[a-z0-9-]+$ to ^x-dre-[a-zA-Z0-9-]+$
• Test Coverage: Added comprehensive tests for configuration and generate functionality

📋 Configuration Features

• Up to 10 configuration items per extension
• User-friendly labels and descriptions
• Automatic header name generation with x-dre- prefix
• Duplicate header validation
• Passed as HTTP headers to extension APIs