Intro skip: parse Jikan v4's actual response shape

Jikan /anime/{id}/episodes returns the episode list DIRECTLY under
'data' (flat array), not {'episodes': [...]}. The old code called
.get() on that list -> AttributeError, swallowed by the endpoint's
except -> [] -> the skip button could never appear, even with Jikan
up. Accept both shapes now.

Verified end-to-end with a mocked /api/intros response: the button is
wired into the player, visible exactly while currentTime is inside the
intro window (111-188s test), hidden outside it.

The live button still awaits Jikan/MAL recovery (504ing since this
feature landed); failures are not cached, so it activates on the first
successful fetch.

Skipped: MAL-direct fallback — official API needs a client key
(403 without), and the keyless HTML page carries no intro data.

server/upstream.py

@@ -132,9 +132,13 @@ def _parse_intros(eps):
 
 
 def _intros(mal_id):
-    """Jikan (keyless MAL mirror): per-episode intro start/length, seconds"""
+    """Jikan (keyless MAL mirror): per-episode intro start/length, seconds."""
+    # Jikan v4 returns the list directly under 'data'; tolerate a wrapped
+    # shape too, so a format change doesn't silently kill the button
     r = _get("https://api.jikan.moe/v4/anime/{}".format(mal_id) + "/episodes")
-    return _parse_intros(r.json().get("data", {}).get("episodes", []))
+    d = r.json().get("data")
+    eps = d if isinstance(d, list) else (d or {}).get("episodes", [])
+    return _parse_intros(eps)
 
 
 def _master_m3u8(ep_id, lang="eng"):