Summary

• Add .m3u (audio/mpegurl), .m3u8 (application/vnd.apple.mpegurl), and .pls (audio/x-scpls) to the content type map in src/utils/url.js
• Add the corresponding MIME types to the mashlib rdfTypes array in src/mashlib/index.js so the data browser serves them

Fixes #228

Test plan

• Verify .m3u files are served with audio/mpegurl content type
• Verify .m3u8 files are served with application/vnd.apple.mpegurl content type
• Verify .pls files are served with audio/x-scpls content type
• Verify mashlib renders these content types when browsing with Accept: text/html