fix: Start playback when Spotify is idle with playNow

When Spotify has no track loaded (idle state), device activation
was returning true, causing QueueTracksAsync to skip starting
playback. Now returns false so caller starts the first track.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: Steven-Marshall

src/Lfm.Spotify/SpotifyStreamer.cs

@@ -1282,7 +1282,7 @@ private async Task<bool> EnsurePlaybackActiveAsync(string? device = null)
             {
                 Console.WriteLine($"✅ Activated device: {activeDevice.Name}");
                 await Task.Delay(1000); // Give Spotify a moment to activate the device
-                return true;
+                return false; // Device ready, but no playback - caller should start first track
             }
         }