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/app.js

@@ -382,6 +382,7 @@ async function showAnime(slug_id, opts = {}) {
   // (ponytail: "first unwatched in list order" is wrong if you skip around;
   //  good enough for sequential viewing)
   epsList = await api(`/api/anime/${seasonId}/episodes`);
+  attachEpNames();
   watchDone = new Set();
   epProg = new Map();
   let started = false;
@@ -657,6 +658,20 @@ function markActive(b) {
   b.classList.add("active");
 }
 
+// episode names (and intro timings) come from the same Jikan call the
+// skip-intro button uses; server caches it 30d and the failure is silent
+function attachEpNames() {
+  const mid = detail && detail.mal_id;
+  if (!mid) return;
+  let p = introCache.get(mid);
+  if (!p) { p = api(`/api/intros/${mid}`).then(t => t || []).catch(() => []); introCache.set(mid, p); }
+  p.then(list => {
+    let changed = false;
+    list.forEach((t, i) => { if (t && t.title && epsList[i]) { epsList[i].name = t.title; changed = true; } });
+    if (changed) renderEps();
+  });
+}
+
 let epsList = [], hideFiller = localStorage.getItem("aniweb_ff") === "1";
 let autoNext = localStorage.getItem("aniweb_auto") !== "0";
 let watchDone = new Set(), watchNext = null, epProg = new Map();
@@ -670,6 +685,8 @@ function renderEps() {
     const b = el("button", "ep" + (e.filler ? " filler" : ""));
     const done = watchDone.has(String(e.id));
     b.textContent = done ? "E" + e.number + " \u2713" : "E" + e.number;
+    if (e.name) b.append(el("span", "ep-name", e.name));
+    b.title = `E${e.number}${e.name ? " — " + e.name : ""}`;
     if (done) b.classList.add("done");
     const pct = epProg.get(String(e.id));
     if (!done && pct != null && pct > 5) {

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; }