v0.9.4: Playlist Sharing

• Playlist Share Code: Each playlist now gets a unique share code (e.g. tapi-4l1Ch)
• /play tapi-xxxxx: Play anyone's shared playlist by entering their share code
• /save now displays the share code in the success message
• Web Share Button: Added Share button to the web playlist page — copies share code to clipboard
• Buy Me a Coffee button added to the playlist page