Add configurable keyboard shortcuts and notifications to the Spotify Web Player Default Keyboard Shortcuts

• Play/Pause: Alt+Shift+W
• Next: Alt+Shift+Right Arrow
• Previous: Alt+Shift+Left Arrow
• Shuffle: Alt+Shift+D
• Repeat: Alt+Shift+R
• Play Album: Alt+Shift+G
• Save Track: Alt+Shift+L
• Mute/Unmute: Alt+Shift+M
• Volume Up: Alt+Shift+Up Arrow
• Volume Down: Alt+Shift+Down Arrow
• Skip Forward: Alt+Shift+Period
• Skip Back: Alt+Shift+Comma

All shortcuts can be customized in Firefox extension settings. Skip duration is configurable (1-60 seconds) in the extension options page.