feat(library): focused music/TV/movie landing screens + self-draining download queue

Library screens:
- Add dedicated music, TV, and movie landing pages (hero banner +
  horizontal carousels) backed by new music/tv/movies stores.
- Route tvshows libraries to /library/tv; surface rediscover ("haven't
  listened to in a while") albums via a new repository method across
  online/offline/hybrid repos plus the repository_get_rediscover_albums
  command.
- Add an A-Z jump bar for long alphabetically-sorted lists, with grid
  index anchors in LibraryGrid/LibraryListView/TrackList.
- Filter the "Podcasts" folder out of music library queries.

Downloads:
- Add a backend queue pump: enqueue_download / enqueue_video_downloads
  persist the resolved stream URL + target dir on each row (migration
  017), and the pump starts up to max_concurrent and drains the rest
  automatically as slots free, instead of the frontend silently dropping
  items past the concurrency limit. Album/series/season buttons now
  enqueue rather than calling start_download directly.

Other fixes:
- Hybrid search now returns instant cache results and pushes the merged
  cache+server union via a request-id-tagged search-event, so superseded
  queries can't clobber fresher results.
- URL-encode SearchTerm / genres / item types in online repo requests.
- Android: pause on audio-becoming-noisy (headphone/BT disconnect).

src-tauri/src/repository/online.rs

@@ -568,6 +568,16 @@ impl MediaRepository for OnlineRepository {
             if let Some(recursive) = opts.recursive {
                 endpoint.push_str(&format!("&Recursive={}", recursive));
             }
+            if let Some(genres) = opts.genres {
+                if !genres.is_empty() {
+                    // Genre names may contain spaces/ampersands, so percent-encode each.
+                    let encoded: Vec<String> = genres
+                        .iter()
+                        .map(|g| urlencoding::encode(g).into_owned())
+                        .collect();
+                    endpoint.push_str(&format!("&Genres={}", encoded.join("|")));
+                }
+            }
         }
 
         // Request image fields for list views (People only needed in get_item detail view)
@@ -759,6 +769,32 @@ impl MediaRepository for OnlineRepository {
         Ok(final_result)
     }
 
+    async fn get_rediscover_albums(
+        &self,
+        parent_id: Option<&str>,
+        limit: Option<usize>,
+    ) -> Result<Vec<MediaItem>, RepoError> {
+        let limit_val = limit.unwrap_or(12);
+        // Ask Jellyfin for played albums sorted by least-recently played first.
+        // Filters=IsPlayed keeps only albums the user has actually listened to,
+        // and SortBy=DatePlayed ascending surfaces the ones they've neglected.
+        let mut endpoint = format!(
+            "/Users/{}/Items?SortBy=DatePlayed&SortOrder=Ascending&IncludeItemTypes=MusicAlbum&Limit={}&Recursive=true&Filters=IsPlayed&Fields=BackdropImageTags,ParentBackdropImageTags",
+            self.user_id, limit_val
+        );
+
+        if let Some(pid) = parent_id {
+            endpoint.push_str(&format!("&ParentId={}", pid));
+        }
+
+        let response: ItemsResponse = self.get_json(&endpoint).await?;
+        Ok(response
+            .items
+            .into_iter()
+            .map(|item| item.to_media_item(self.user_id.clone()))
+            .collect())
+    }
+
     async fn get_resume_movies(&self, limit: Option<usize>) -> Result<Vec<MediaItem>, RepoError> {
         let limit_str = limit.unwrap_or(16);
         let endpoint = format!(
@@ -811,14 +847,24 @@ impl MediaRepository for OnlineRepository {
         options: Option<SearchOptions>,
     ) -> Result<SearchResult, RepoError> {
         let limit = options.as_ref().and_then(|o| o.limit).unwrap_or(50);
+        // SearchTerm is arbitrary user input and must be percent-encoded so that
+        // spaces, ampersands, etc. don't corrupt the query string (a multi-word
+        // search like "Star Wars" would otherwise produce a malformed URL).
         let mut endpoint = format!(
             "/Users/{}/Items?SearchTerm={}&Limit={}&Recursive=true",
-            self.user_id, query, limit
+            self.user_id,
+            urlencoding::encode(query),
+            limit
         );
 
         if let Some(opts) = options {
             if let Some(types) = opts.include_item_types {
-                endpoint.push_str(&format!("&IncludeItemTypes={}", types.join(",")));
+                let encoded_types = types
+                    .iter()
+                    .map(|t| urlencoding::encode(t).into_owned())
+                    .collect::<Vec<_>>()
+                    .join(",");
+                endpoint.push_str(&format!("&IncludeItemTypes={}", encoded_types));
             }
         }
 
@@ -1768,4 +1814,13 @@ mod tests {
         assert_eq!(response.items[0].id, "item1");
         assert_eq!(response.items[1].id, "item2");
     }
+
+    #[test]
+    fn test_search_term_is_url_encoded() {
+        // A multi-word query (and one with a reserved character) must be
+        // percent-encoded before being placed in the SearchTerm query param,
+        // otherwise the request URL is malformed and search returns nothing.
+        assert_eq!(urlencoding::encode("Star Wars"), "Star%20Wars");
+        assert_eq!(urlencoding::encode("Tom & Jerry"), "Tom%20%26%20Jerry");
+    }
 }