vc=32 fix: drop SearchItem.uploader_avatar — not on StreamInfoItem

I confused StreamInfo (the big single-video struct, has
uploader_avatars: ImageSet) with StreamInfoItem (the card struct used
in search results / channel video lists / related streams — no
uploader_avatars field). cargoBuildHost caught it: E0609 no field
`uploader_avatars`.

Drop the field from SearchItem (and from the Kotlin construction
sites). For the subs feed and "more from this channel" we already
use the channel-level avatar from ChannelInfo.avatar, which is the
right granularity anyway (every video from one channel shares one
avatar). Per-card uploader avatars on search/related stay null until
strawcore-core extracts them on StreamInfoItem too.

rust/strawcore/src/search.rs

@@ -15,7 +15,6 @@ pub struct SearchItem {
     pub title: String,
     pub uploader: String,
     pub uploader_url: Option<String>,
-    pub uploader_avatar: Option<String>,
     pub thumbnail: Option<String>,
     /// Duration in seconds. 0 = live/unknown.
     pub duration_seconds: i64,
@@ -37,16 +36,11 @@ pub(crate) fn from_core(item: StreamInfoItem) -> SearchItem {
         .thumbnails
         .last()
         .map(|i| i.url().to_string());
-    let uploader_avatar = item
-        .uploader_avatars
-        .last()
-        .map(|i| i.url().to_string());
     SearchItem {
         url: item.url,
         title: item.name,
         uploader: item.uploader_name,
         uploader_url,
-        uploader_avatar,
         thumbnail,
         duration_seconds: item.duration_seconds,
         view_count: if item.view_count < 0 {