2020-2-28 major update: music library, music channels and related features

I have long considered a music library and music channels in the cms, but existing music playback and download sites and their players felt too uniform. Recently, a modern player technology on an overseas technical blog inspired me to spend several days completing the library and cms audio programs. I also added article background uploads and frontend display, and fixed reported BUG issues.

2020-2-28 features

• One: Music-library management supports uploading audio and editing titles, artists, albums and covers.
• Two: Added music programs in the cms. Create playlists or audio courses, import edited library tracks into a list, and the cms displays a music channel with a modern player and a different experience.
• Three: Articles support optional background-image uploads. The frontend uses the uploaded background or its default when absent.
• Four: Added CAPTCHA sign-in to the CMS and improved mobile sign-in placement.
• Five: Added a more complete ad-management system to the CMS.
• Six: Fixed known BUG issues and refined code for better stability.