recents: a streamed album has no library id, so the key must not pretend it does

The sidebar history looked completely dead -- albums never appeared, the
list never updated, and often nothing was there at all. The backend was
fine the whole time: 460 play rows, recent_albums returning every album
correctly.

The list is a keyed each on `a:${album_id}`, but catalog-anchored rows --
every streamed play -- carry album_id NULL by design and are identified by
catalog_album_id. One streamed album in history keyed `a:null` harmlessly.
The second one collided with it, the keyed each threw, and the whole list
unmounted; every later refresh fed a dead component. It demoed clean
yesterday only because history had just been wiped and exactly one
streamed album existed.

Keys now carry the id realm, the same two-realm split isPlaying and
openRecent already used.

src/components/Sidebar.svelte

@@ -82,7 +82,15 @@
                 day = k;
                 rows.push({ kind: "day", label: k, key: `d:${k}` });
             }
-            rows.push({ kind: "album", album: a, key: `a:${a.album_id}` });
+            // Two id realms, so the key must carry the realm: catalog rows
+            // have album_id NULL, and keying them all `a:null` was a
+            // duplicate-key crash that silently killed this whole list the
+            // moment TWO streamed albums entered history (2026-08-01).
+            rows.push({
+                kind: "album",
+                album: a,
+                key: a.kind === "catalog" ? `c:${a.catalog_album_id}` : `l:${a.album_id}`,
+            });
         }
         return rows;
     });