feat: Add folder support with drag & drop

[dernerl]

📁 Folder Support Implementation

Closes #4

✅ Implemented Features

1. Data Model & Persistence

• SwiftData model extended with:
  • parentID: UUID? - Hierarchical structure (nil = root level)
  • isFolder: Bool - Distinguish folders from favorites
  • order: Int - Sorting within the same level
• Automatic migration with default values

2. User Interface

• 📂 Folder display with DisclosureGroup (collapsible)
• ➕ "Add Folder" button in toolbar (CMD+N)
• ➕ "Add to Folder" button inside each folder
• Hierarchical display with proper indentation
• Consistent section headers (Favorites & Generated Outputs)

3. Drag & Drop

• 👆 Move favorites between root and folders
• 🔄 Reorder items within same level
• Drop zones before/after each item
• Drop zone at start of lists (for first position)
• Validation:
  • ❌ Folders cannot be nested (only 1 level deep)
  • ❌ Folders cannot be dropped into themselves
  • ✅ Favorites can move freely between root and folders

4. Export (JSON & Plist)

• JSON Format (Windows/GPO & Intune Settings Catalog):

  {
    "name": "Work Links",
    "children": [
      { "name": "GitHub", "url": "https://github.com" }
    ]
  }

• Plist Format (macOS/Intune Configuration Profiles):

  <dict>
    <key>children</key>
    <array>...</array>
    <key>name</key>
    <string>Work Links</string>
  </dict>

• Correct Microsoft Edge format (children before name in Plist)
• Sorted by order field for consistent output

5. UX Improvements

• ⚙️ TopLevel Name moved to Settings (⌘,)
  • Cleaner main view
  • No drag & drop conflicts
  • Semantically correct location
• Improved section headers with subtitles
• Better visual consistency

📝 Changes Overview

Modified Files:

• Favorite.swift - Data model with hierarchy fields
• FavoritesViewModel.swift - Folder management & drag & drop logic
• ContentView.swift - Drag & drop UI implementation
• FolderRowView.swift - Folder display component
• FormatGenerator.swift - JSON/Plist generation with children arrays
• SettingsView.swift - TopLevel Name configuration
• AppKitTextField.swift - Drag & drop protection (not needed after Settings move)

🧪 Testing

Tested Scenarios:

• ✅ Create folders and add favorites
• ✅ Drag favorites into folders
• ✅ Drag favorites out of folders
• ✅ Reorder items via drag & drop
• ✅ Export JSON/Plist with folder structure
• ✅ TopLevel Name in Settings
• ✅ SwiftData persistence across app restarts

📦 Version

This PR prepares for v1.1.0 release (MINOR version bump - new features, backward compatible)

📸 Screenshots

Main View with Folders:

• Folder hierarchy with disclosure triangles
• Drag & drop visual feedback
• Clean section headers

Settings:

• TopLevel Name configuration
• Version info

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Ready for review and merge into main! 🚀