iOS 1.0.2: shuffle the whole library from Songs

Shuffle used only the pages loaded so far (the A and B songs). It now
asks Plex for 1000 random tracks from the whole library.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/Stemify/Plex/PlexClient.swift

@@ -132,6 +132,11 @@ final class PlexClient: @unchecked Sendable {
         return (c.metadata.map { $0.toTrack() }, c.totalSize ?? c.size)
     }
 
+    /// Random tracks from the whole library, for shuffling it without loading every page.
+    func randomTracks(_ count: Int) async throws -> [Track] {
+        try await get("/library/sections/\(section)/all", [("type", 10), ("sort", "random")], start: 0, size: count).metadata.map { $0.toTrack() }
+    }
+
     func album(_ key: String) async throws -> Album? {
         try await get("/library/metadata/\(key)").metadata.first?.toAlbum()
     }