feat: playback completion signal test scenes

[pravusjif]

Related PRs:

• feat: emote state in avatarEmoteCommand protocol#459
• feat: emote state in avatarEmoteCommand (experimental) protocol#458
• feat: audioEventSystem + avatarEmoteCommand.state (experimental) js-sdk-toolchain#1516
• feat: audioEventSystem + avatarEmoteCommand.state js-sdk-toolchain#1530
• feat: sdk audio, animation, emotes playback completion signals unity-explorer#9589
• feat: playback completion signals docs#157
• feat: playback completion signals sdk-skills#70

[github-actions]

How to test scene changes in the SEPOLIA World

Every commit pushed to any branch automatically triggers the deployment of the modified scenes to the sdk7testscenes.dcl.eth world on SEPOLIA.

If you need to re-trigger that deployment manually:

1. Go to the Deploy changed scenes to world action
2. Click Run workflow, select your branch, and enter the scene folder (e.g. scenes/88,-10-audio-visualization)

Once deployed, test the scene in the Explorer:

1. Switch MetaMask to the SEPOLIA network (not mainnet)
2. Open the Explorer using one of these methods:
   • Jump-in link (any browser): http://decentraland.zone/jump/?dclenv=zone&realm=sdk7testscenes.dcl.eth&position=4,23
   • Deep link (any browser): decentraland://?dclenv=zone&realm=sdk7testscenes.dcl.eth&position=4,23
   • Custom build: launch with --dclenv zone --realm sdk7testscenes.dcl.eth --position 4,23 app params — instructions
   • Unity Editor: set Decentraland Environment to zone and Init Realm to sdk7testscenes.dcl.eth