v10.0.0-beta.1

Video.js 10 is in beta. This release flips the npm dist-tags from alpha/next to beta/latest (#846): npm install @videojs/html now installs v10 without the @next suffix, and install commands, CDN URLs, and badges across the docs drop it too. The next tag stays frozen at 10.0.0-alpha.10. Package READMEs, the contributing guide, and the release manifest were updated to match (#847, #848, #850). The site also gains ejected skins (#809): a build script generates copy-paste source for all four skins across HTML and React, in CSS and Tailwind variants, powering a new customize-skins docs page and the home page’s “Take full control” demo.