Connect macOS app to backend device bootstrap

packages/apple/VelodySync/Sources/VelodySync/PlaceholderSyncCoordinator.swift

@@ -36,28 +36,13 @@ public actor PlaceholderSyncCoordinator: SyncCoordinator {
     }
 
     public func performInitialSync() async throws -> SyncResult {
-        let health = try await apiClient.fetchHealthStatus()
-        let existingTracks = await store.loadTracks()
-        let tracks: [LibraryTrack]
-
-        if existingTracks.isEmpty {
-            tracks = [
-                LibraryTrack(
-                    title: "Velody Placeholder",
-                    artist: "Private Library",
-                    album: "Phase 1",
-                    localFilePath: ""
-                ),
-            ]
-            await store.replaceTracks(tracks)
-        } else {
-            tracks = existingTracks
-        }
+        let bootstrap = try await apiClient.fetchSyncBootstrap()
+        await store.replaceTracks(bootstrap.tracks)
 
         return SyncResult(
-            statusMessage: "Sync placeholder ready (\(health.databaseStatus)/\(health.storageStatus))",
-            tracks: tracks,
-            cursor: SyncCursor(value: "0")
+            statusMessage: "Sync bootstrap completed. Tracks: \(bootstrap.tracks.count). Next cursor: \(bootstrap.nextCursor.value).",
+            tracks: bootstrap.tracks,
+            cursor: bootstrap.nextCursor
         )
     }
 }