Version 1.3.15

[maboa]

A point release fixing the intro's poster on launch.

• Firefox: the intro's player shows the markup poster while the popout shows the glyph #621 — the intro's player wore the markup poster on launch while the Recents popout drew the glyph, seen in Firefox on 1.3.14. The intro's medium is in the markup and starts loading before any script, so a cached mp3 could report metadata before media-first-frame had a listener, and the pass that draws the glyph never ran. The module now settles a medium whose metadata is already known when it wires up, and a library change settles audio still wearing the markup poster.

Fixes #621

Gate: 105 unit; 322 e2e passed, 1 skipped (the known WebKit OPFS skip).