feat: Add right-click folder creation in sidebar

[Builder14122]

Add Right-Click Folder Creation to Sidebar

Summary

This PR introduces the ability to create folders in the sidebar through a right-click context menu, allowing users to better organize their tabs hierarchically.
AI Disclosure: This was all done with Opus 4.1

What's Changed

Core Features

• Right-click context menu: Right-clicking anywhere in the sidebar now shows a "Create New Folder" option
• Folder management: Users can create, rename, and delete folders
• Tab organization: Tabs can be dragged into folders or moved via context menu
• Expand/Collapse: Folders can be expanded or collapsed to show/hide their contents
• Visual indicators: Folder icons and tab counts are displayed for easy navigation

Technical Implementation

Data Model Changes

• Enhanced Folder model to support tabs with an order property
• Added folder relationship to Tab model for organizing tabs into folders
• Maintained backward compatibility with existing tab structures

New Components

• FolderView: Displays folders in the sidebar with expand/collapse functionality
• CreateFolderSheet: Dialog for creating new folders
• FolderDropDelegate & FolderTabDropDelegate: Handle drag-and-drop operations

Updated Components

• ContainerView: Added right-click context menu and folder display logic
• TabItem: Enhanced context menu with folder management options
• TabManager: Added methods for folder operations (create, rename, delete, move tabs)

Screenshots/Demo

[Add screenshots or GIF showing the feature in action]

1. Right-clicking in the sidebar to show context menu
2. Creating a new folder
3. Dragging tabs into folders
4. Expanding/collapsing folders

Testing

• ✅ Build succeeds without errors
• ✅ Right-click context menu appears correctly
• ✅ Folders can be created with custom names
• ✅ Tabs can be dragged into folders
• ✅ Folders can be expanded/collapsed
• ✅ Folders can be renamed by double-clicking
• ✅ Empty folders can be deleted
• ✅ Folders with tabs show confirmation before deletion
• ✅ Tabs can be moved between folders via context menu

Compatibility

• Requires macOS 14.0+
• Compatible with existing tab management features
• No breaking changes to existing functionality

Future Enhancements

• Nested folders support
• Keyboard shortcuts for folder operations
• Folder color/icon customization
• Bulk tab operations within folders
• Folder templates/presets

Related Issues

This feature addresses the need for better tab organization in the sidebar, as discussed in community feedback.

Checklist

• Code follows the project's style guidelines
• Self-review completed
• Code builds without warnings
• Feature tested on macOS
• No existing functionality broken
• Documentation updated (if applicable)

How to Test

1. Clone this branch
2. Run xcodegen to generate the Xcode project
3. Build and run the app
4. Right-click in the sidebar area
5. Select "Create New Folder"
6. Try dragging tabs into the folder
7. Test renaming (double-click folder name) and deletion (right-click folder)

Notes for Reviewers

• The implementation uses SwiftUI's native context menu and drag-and-drop APIs
• Folder state persistence is handled through the existing SwiftData framework
• The UI follows the existing design patterns in the Ora browser

Please test the feature thoroughly and provide feedback on:

• UI/UX improvements
• Edge cases that need handling
• Performance with many folders/tabs
• Integration with other features