fix(ui): a picture that fails to load shows the card's own frame, then retries

A bare <img> sent a Referer that Google's image CDNs refuse and had no retry and no fallback, so a
Home shelf card showed the browser's broken-image mark. ui/RemoteImage gathers what Avatar, the
channel banner and the download rows had each hand-rolled: no Referer, up to three retries past the
browser's negative cache, the caller's fallback (by default the card's empty frame) instead of the
broken mark, the failure remembered by URL. Every picture now goes through it; a lint rule refuses
a bare <img>.

frontend/src/components/PlexLibraryPicker.tsx

@@ -6,6 +6,7 @@ import { api, type PlexCard } from "../lib/api";
 import { useDebounced } from "../lib/useDebounced";
 import { LoadingState } from "./ui/QueryState";
 import { cardImage } from "../lib/plexImage";
+import RemoteImage from "./ui/RemoteImage";
 
 // A debounced library search-and-pick list, shared by the "Add title" panel (PlexCollectionView) and
 // the "New collection" first-title panel (plexBrowseLists) — both search the library the same way and
@@ -49,7 +50,7 @@ export default function PlexLibraryPicker({
     <ul className="flex flex-col gap-1">
       {results.map((c) => (
         <li key={c.id} className="flex items-center gap-3">
-          <img
+          <RemoteImage
             {...cardImage(c.thumb)}
             alt=""
             className="h-12 w-8 shrink-0 rounded object-cover"