Stemify iOS 1.1 and WebUI updates, repo restructure into desktop/ios/server/web

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

ios/Stemify/CarPlay/CarLibrary.swift

@@ -76,7 +76,7 @@ final class CarLibrary: @unchecked Sendable {
         default:
             guard let (kind, key) = CarIds.split(id) else { return nil }
             switch kind {
-            case "playlist": return await songs(id, try tracksOf(id), shuffleRow: true, showArtist: true)
+            case "playlist", "stemplaylist": return await songs(id, try tracksOf(id), shuffleRow: true, showArtist: true)
             case "album": return await songs(id, try tracksOf(id), shuffleRow: false, showArtist: false)
             case "artist": return try await artistPage(key, away)
             case "albums": return try await albumsFor(away).filter { CarTree.letterOf($0.title) == key }.map { albumItem($0) }
@@ -95,7 +95,13 @@ final class CarLibrary: @unchecked Sendable {
         } else {
             shown = all
         }
-        return shown.map { playlistItem($0) }
+        let stem = await MainActor.run { AppGraph.shared.stemPlaylists.lists.filter { !$0.items.isEmpty } }
+        let stemItems = stem.map { l in
+            CarItem(id: "stemplaylist:\(l.id)", title: l.title, subtitle: CarTree.countLabel(l.items.count, "song", "songs"),
+                    art: artOr(l.thumb, l.title), playable: false, group: "Stem Playlists")
+        }
+        let plexItems = shown.map { playlistItem($0, group: stemItems.isEmpty ? nil : "Plex Playlists") }
+        return stemItems + plexItems
     }
 
     private func albumsTab(_ away: Bool) async throws -> [CarItem] {
@@ -168,6 +174,7 @@ final class CarLibrary: @unchecked Sendable {
             guard let (kind, key) = CarIds.split(container) else { return [] }
             switch kind {
             case "playlist": all = try await plex.playlistTracks(key)
+            case "stemplaylist": all = await MainActor.run { AppGraph.shared.stemPlaylists.list(key)?.tracks ?? [] }
             case "album": all = try await plex.albumTracks(key)
             case "artist": all = away ? downloadedTracks().filter { $0.artistKey == key } : try await plex.artistTracks(key)
             case "search": all = try await searchTracks(key, away)