Episode names: render MAL titles on the episode grid

anidb's episodes API has no names (id/number/filler only), but the
Jikan call we already make for intro timings carries them (title +
title_japanese). _parse_intros now keeps one entry per episode with
title and optional start/length (entries are never null anymore).

Client: attachEpNames() reuses the introCache promise, stamps
epsList[i].name, re-renders; buttons show the name (3-line clamp) +
full tooltip. Jikan down => no names, no error (same graceful
degradation as the skip-intro button).

Verified headless: Jujutsu Kaisen S1 24/24 buttons named
('E1 | Ryomen Sukuna' ...); S2 (Jikan 504 at the time) rendered
gracefully without names. 17/17 API tests.

static/style.css

@@ -164,6 +164,8 @@ button.tiny.on { border-color: var(--acc); color: var(--acc); }
 
 .eps { display: grid; grid-template-columns: repeat(auto-fill, minmax(64px, 1fr)); gap: 0.4rem; }
 .ep { position: relative; font-size: 0.9rem; }
+.ep-name { display: -webkit-box; -webkit-line-clamp: 3; -webkit-box-orient: vertical;
+  overflow: hidden; font-size: .68rem; color: var(--muted); margin-top: .2rem; line-height: 1.2; }
 .ep.filler { opacity: 0.55; }
 .ep.done { opacity: 0.5; }
 .ep.nextup { border-color: #4b5568; background: #1f2130; }