feat: Implement LXC settings

[michelroegl-brunner]

Summary

This PR adds a new LXC settings modal for managing container configurations directly from the web interface.

New Features

✨ LXC Settings Modal

• Complete LXC configuration management with a user-friendly interface
• Real-time configuration editing with form validation
• Sync from server functionality to pull current container settings
• Save to server with proper confirmation and safety checks
• Tabbed interface with Common Settings and Advanced Settings sections

🔧 Configuration Management

• Basic Configuration: Architecture, cores, memory, hostname, OS type, etc.
• Network Configuration: Interface settings, bridge, MAC address, IP configuration
• Storage Settings: Root filesystem storage and size configuration
• Feature Toggles: Keyctl, nesting, FUSE, and additional mount features
• Advanced Settings: Raw configuration editing for power users

🛡️ Safety Features

• Confirmation modal with container ID verification before saving
• Change detection to only enable save when modifications are made
• Error handling with clear user feedback
• SSH connection validation before attempting operations

User Experience

• Intuitive interface with contextual help icons
• Real-time validation and form state management
• Loading states and progress indicators
• Success/error messaging for all operations

Technical Implementation

• tRPC integration for type-safe API calls
• Prisma database integration for configuration storage
• SSH execution for server communication
• React hooks for state management and side effects

Files Added

• src/app/_components/LXCSettingsModal.tsx - Main modal component
• Database schema updates for LXC configuration storage
• API endpoints for configuration management

This modal provides a complete solution for managing LXC container configurations without needing direct server access.