Intro skip: MAL timings via keyless Jikan + player button

- upstream: _intros(mal_id) -> per-episode {start,length} (seconds),
  30d TTL cache; Jikan is down or show uncovered -> [] (no button)
- app: GET /api/intros/{mal_id}, never errors into the player
- player: 'skip intro' pill appears while currentTime is inside the
  intro window (+8s grace); click seeks past; reappears if rewound.
  Ep-1 intros are often missing in MAL data, so falls back to the
  show's first known timing (usually identical across eps)
- test: _parse_intros unit test (Jikan itself is 504ing right now,
  live path verified by hand: endpoint returns [] cleanly)

static/app.js

@@ -840,6 +840,7 @@ async function play(ep_id, ep_no) {
       blocked();
     });
     watchPos(v);
+    setupIntro(v, ep_no);
     postHistory({...meta(v), title: detail.name, slug_id: detail.slug_id, season_id: seasonId,
                  ep_id, lang, ep: ep_no, pos: saved?.pos || 0});
   } catch (e) {
@@ -848,6 +849,34 @@ async function play(ep_id, ep_no) {
   document.title = `${detail.name} E${ep_no} — ani-web`;
 }
 
+// ---------- intro skip (MAL timings via keyless Jikan, cached server-side) ----------
+const introCache = new Map();  // mal_id -> Promise<timings>
+function setupIntro(v, epNo) {
+  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 => {
+    if (!currentEp || currentEp.v !== v) return;  // superseded by a newer play()
+    // ponytail: ep 1 intros are often missing in MAL data; fall back to the
+    // show's first known timing (intros are usually identical across eps)
+    let t = list[epNo - 1];
+    if (!t) for (const x of list) if (x) { t = x; break; }
+    if (!t || !(t.length > 0)) return;
+    const s = t.start, e = t.start + t.length;
+    let skipped = false;
+    const b = el("button", "skip-intro", "skip intro \u23ed");
+    b.hidden = true;
+    b.onclick = () => { v.currentTime = e + 0.5; skipped = true; b.hidden = true; };
+    document.getElementById("player").append(b);
+    v.addEventListener("timeupdate", () => {
+      if (skipped && v.currentTime < s) skipped = false;  // user rewound back to the window
+      if (skipped) return;
+      b.hidden = !(v.currentTime >= s && v.currentTime <= e + 8);
+    });
+  });
+}
+
 // extra fields to persist with every history entry (progress + poster)
 const meta = v => ({...(Number.isFinite(v.duration) && v.duration > 0 ? {dur: v.duration} : {}),
                      poster: detail ? (detail.poster || null) : null});

static/style.css

@@ -110,6 +110,9 @@ h2 { margin: 0.4rem 0; }
 
 .player { position: relative; }
 .player video { width: 100%; max-height: 70vh; background: #000; border-radius: 10px; aspect-ratio: 16/9; }
+.skip-intro { position: absolute; right: .8rem; bottom: 3rem; z-index: 2;
+  padding: .4rem 1rem; border-radius: 99px; border: 1px solid var(--acc);
+  background: rgba(14, 15, 19, .85); color: var(--fg); font-size: .9rem; cursor: pointer; }
 .controls { display: flex; align-items: center; gap: 0.4rem; margin: 0.6rem 0; flex-wrap: wrap; }
 button { background: var(--card); color: var(--fg); border: 1px solid var(--bd);
   border-radius: 8px; padding: 0.4rem 0.7rem; cursor: pointer; }