docs(jellyfin): episode stills are out of scope, and the cost that says so

A per-episode RemoteImages query is never cached, so the same campaign that
dressed 620 series in an afternoon costs ~11 s per episode for one hit in five.
Across 42k episodes that is days of provider traffic to dress a fifth of them, and
clients show series and season art regardless. Recorded so nobody runs the pass on
a hunch; the door and the resumable log are the same if Frank orders it.

serverAppConfigs-docs/Dankserver/Jellyfin.md

@@ -130,6 +130,13 @@ nothing to look up. Art coverage is capped by identification, not by the image d
 the items a campaign returns nothing for are the unidentified ones, and no image
 retry will change that.
 
+**Series and season art is fetched; episode stills are not, deliberately.** Every
+episode query is a fresh provider round-trip — nothing caches per episode — measured
+at ~11 s per item beside ~2 s per series on the same host, with one hit in five in a
+sample. Across 42k episodes that is days of provider traffic to dress a fifth of them,
+and clients display the series and season art anyway. If episode stills are ever
+ordered, the loop is the same door and its log makes the pass resumable.
+
 **API shape on 12.x:** `/Items` and `/Items/{id}` need `UserId` when
 authenticated by API key — without it the answer is `400 Error processing
 request`, which reads exactly like an authentication failure. `MetadataRefreshMode`