Add custom disc management and fullscreen display

[PhayMo]

Features added:

• Custom disc management for CD/DVD/Blu-ray
• Add, edit, and delete custom discs with cover art
• Fullscreen now-playing display with SignalR
• Modern Apple-inspired UI redesign
• Smart disc selection and search functionality
• Improved popover handling and scrolling
• Toggle visibility for CD and Movie sections

[PhayMo]

Features Added

Custom Disc Management

• Add custom CDs, DVDs, and Blu-ray discs without scanning
• Edit disc metadata (title, artist, tracks, cover art)
• Upload custom cover art images
• Assign and change disc slots
• Delete custom discs
• Separate storage in CustomDiscs.json

Fullscreen Display

• Real-time now-playing display using SignalR (wwwroot/fullscreen.html)
• Shows album art, track info, and disc details
• Keyboard controls for playback (3=Previous, Enter=Play/Pause, 7=Next)
• Auto-hide cursor in fullscreen mode
• Modern minimalist design

UI Improvements

• Modern Apple-inspired design language
• Improved disc grid layout with proper aspect ratios
• Scrollable popovers with sticky action buttons
• Smart random disc selection with visual feedback
• Search functionality across all discs
• Collapsible top bar with compact mode
• Toggle visibility for CD and Movie sections
• Disc counts per changer
• Editable library name

Technical Changes

• Added Models/CustomDiscService.cs for custom disc management
• Added Models/CustomDisc.cs model
• Added Pages/AddCustomDisc.cshtml(.cs) for adding/editing discs
• Modified Hubs/DiscChangerHub.cs to support custom disc operations
• Enhanced Pages/Index.cshtml with modern CSS and JavaScript
• Added wwwroot/fullscreen.html for now-playing display
• Modified Startup.cs to add CORS policy for fullscreen

Files Modified

• Enhanced: Pages/Index.cshtml, wwwroot/css/site.css, wwwroot/js/discchanger.js
• New: Models/CustomDisc.cs, Models/CustomDiscService.cs
• New: Pages/AddCustomDisc.cshtml, Pages/AddCustomDisc.cshtml.cs
• New: wwwroot/fullscreen.html
• Modified: Hubs/DiscChangerHub.cs, Startup.cs

Backward Compatibility

• All existing functionality preserved
• Scanned disc data format unchanged
• Custom disc data stored separately in wwwroot/CustomDiscs.json
• No breaking changes to core features

Testing

• Tested custom disc addition, editing, and deletion
• Verified disc slot assignment and reassignment
• Tested fullscreen display with SignalR updates
• Verified all UI features and responsive behavior
• Confirmed scanning functionality remains intact

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