fix(spotify): include sid/sn in track enqueue uri

[WinnCook]

Fixes #5

Repro

sonos play spotify "August 10 Khruangbin" --name "Kitchen"

What changed

• try x-sonos-spotify:<encoded-id>?sid=<service>&sn=0 first for track/episode queue URIs
• preserve existing DIDL metadata and service-token descriptor generation
• keep the two legacy URI forms as explicit fallbacks for compatibility

Validation

• added a regression fixture where AddURIToQueue succeeds only when the sid/sn form is used
• added a fallback fixture where the sid/sn form returns UPnP 800 and the legacy URI still succeeds
• go test ./internal/sonos ./internal/cli