fix playback: vendor hls.js locally, surface stream/API errors visibly

- jsdelivr CDN was a silent single point of failure (Hls undefined ->
  unhandled rejection -> black screen with no feedback)
- play() now catches API errors; hls fatal + video media errors render
  'Stream error: ...' under the player
- server now binds 0.0.0.0 (LAN access); was 127.0.0.1 only

static/app.js

@@ -24,6 +24,12 @@ function fail(err) {
   main.append(el("p", "error", "Error: " + err.message));
 }
 
+function showStreamError(msg) {
+  const p = el("p", "error", "Stream error: " + msg);
+  const player = document.getElementById("player");
+  if (player) player.append(p); else fail(new Error(msg));
+}
+
 // ---------- history ----------
 const HKEY = "aniweb.history";
 const hist = () => JSON.parse(localStorage.getItem(HKEY) || "[]");
@@ -139,14 +145,26 @@ function videoEl() {
 function stopHls() { if (hls) { hls.destroy(); hls = null; } }
 
 async function play(ep_id, ep_no) {
-  const s = await api(`/api/episode/${ep_id}/stream?lang=${lang}`);
-  stopHls();
-  const v = videoEl();
-  document.getElementById("player").replaceChildren(v);
-  if (!Hls.isSupported()) throw new Error("HLS not supported in this browser");
-  hls = new Hls();
-  hls.loadSource("/stream/" + s.token);
-  hls.attachMedia(v);
+  try {
+    const s = await api(`/api/episode/${ep_id}/stream?lang=${lang}`);
+    stopHls();
+    const v = videoEl();
+    document.getElementById("player").replaceChildren(v);
+    if (!window.Hls || !Hls.isSupported()) throw new Error("HLS not supported in this browser");
+    hls = new Hls();
+    hls.on(Hls.Events.ERROR, (_, data) => {
+      if (data.fatal) {
+        showStreamError(`${data.type}: ${data.details}` +
+          (data.response ? ` (HTTP ${data.response.code})` : ""));
+        stopHls();
+      }
+    });
+    hls.loadSource("/stream/" + s.token);
+    hls.attachMedia(v);
+    v.onerror = () => showStreamError("media error: " + (v.error?.message || v.error?.code));
+  } catch (e) {
+    showStreamError(e.message);
+  }
   pushHistory({title: detail.name, slug_id: detail.slug_id, season_id: seasonId,
                ep_id, lang, ep: ep_no});
   document.title = `${detail.name} E${ep_no} — ani-web`;