v1.4.0: App update check, download improvements, UI polish

v1.3.0: Stability & UX improvements, new features

New features:
- Error mapping with user-friendly German messages
- Estimated file size display before download
- Auto-retry with exponential backoff for transient errors
- Download history with duplicate detection
- Batch download mode (multiple URLs)
- Full German translation

Stability fixes:
- Fix race conditions: safe ID-based download array access (updateDownload helper)
- Atomic file saving prevents JSON corruption on crash
- Progress clamping to 0-100% for HLS streams
- Prevent multiple concurrent update processes
- Global process limit (max 8 yt-dlp processes)
- Drag & Drop sets URL without auto-starting download
- Disk space check before starting downloads
- Thread-safe process output collectors (Swift 6 ready)
- Reduced prefetch concurrency from 10 to 4

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Add major feature update: Menu Bar, Drag & Drop, and more

Features:
- Menu Bar icon with quick download access and status
- Drag & Drop URLs onto the window to start downloads
- Format presets (Best Quality, Balanced, Mobile, Podcast, Music)
- Download queue management with pause all/resume all
- Clipboard monitoring for auto-detecting video URLs
- Download speed and ETA display during downloads
- Chapter embedding in MP4 videos
- Thumbnail saving option
- Subtitle download support
- macOS notifications on download completion
- Auto-organization by channel/date/playlist

UI improvements:
- Redesigned Menu Bar popup with better styling
- Queue controls header with download counter
- Drag & drop reordering of downloads
- Move up/down buttons for queue management

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add disclaimer and Buy me a coffee section to README

- Add full disclaimer matching the in-app notice
- Add fun "Support the Project" section with Buy Me a Coffee link
- Every coffee = One less bug (probably) ☕🐛

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Fix country: Made in Switzerland 🇨🇭

Add automated release script

- Build, sign, notarize, and publish in one command
- Creates GitHub release with auto-generated notes
- Handles notarization stapling for Gatekeeper

Usage: ./scripts/release.sh 1.2.0

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add dynamic quality picker, prefetch optimization, and UX improvements

- Add dynamic video quality picker showing available formats per video
- Implement background prefetch of video info when URL is pasted
- Show funny rotating status messages during loading
- Auto-paste video URLs from clipboard when app becomes active
- Add all quality options (4K, 1440p, 1080p, 720p, 480p, 360p)
- Improve download status with preparing state
- Increase action button sizes for better usability
- Optimize yt-dlp arguments for faster extraction

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add playlist support, parallel downloads, and performance optimizations

Features:
- Playlist detection and download dialog (choose 10/25/50/100/all videos)
- Parallel downloads (5 simultaneous) for playlists
- Fast video info fetching with --print instead of --dump-json
- Instant YouTube thumbnail generation (no network request)
- Progress tracking that prevents backwards jumps
- Background yt-dlp update checking

UI improvements:
- Loading indicator for playlist fetching
- Playlist badge when playlist URL detected
- Fixed progress percentage display

Performance:
- Download starts immediately while info loads in parallel
- Thumbnail URLs generated locally from video ID
- Setup caching to avoid repeated binary checks
- Optimized yt-dlp arguments for faster extraction

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Revise README for detailed project overview

Updated the README to provide a more detailed project description, including technology stack, goals, and phases of development. Added specific tasks and clean code tips for each phase.