Add idle frame handling and document frame lifecycle

[EmmanuelTheCreator]

Summary

• add an idle frame message interface and plumb idle dispatch through the clock and event mediator
• document sprite/moviel lifecycle methods and ensure BlingoMovie raises events in Director order with idle throttling
• add reusable fake movie builder plus unit tests that assert frame and transition event ordering

Testing

• dotnet test Test/BlingoEngine.Tests/BlingoEngine.Tests.csproj

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https://chatgpt.com/codex/tasks/task_e_68d3ddb960b48332a5c48f3f6161c11f