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.

tests/test_api.py

@@ -312,3 +312,33 @@ def test_parse_intros():
         None,
         None,
     ]
+
+
+def test_intros_parses_jikan_shapes():
+    # _intros against a stubbed HTTP layer: Jikan v4 returns the episode
+    # list directly under 'data' (not {'episodes': [...]}) — a regression
+    # here would silently disable the skip button whenever Jikan is up.
+    import server.upstream as u
+
+    class R:
+        def json(self):
+            return {"data": [
+                {"title": "Episode 1", "intro": {"start": 111, "length": 77}},
+                {"title": "Episode 2", "intro": {"start": 0, "length": 0}},
+            ]}
+
+    u._CACHE.clear()
+    u._get = lambda url: R()  # stub the network
+    assert u._intros(92573) == [
+        {"start": 111, "length": 77},
+        {"start": 0, "length": 0},
+    ]
+    # wrapped shape still works
+    class W:
+        def json(self):
+            return {"data": {"episodes": [
+                {"intro": {"start": 90, "length": 60}},
+            ]}}
+    u._get = lambda url: W()
+    assert u._intros(92573)[0]["start"] == 90
+    u._CACHE.clear()