Recording a program should disable on-screen debug controls

There's a button to record programs in CodeWorld. There is also a on-hover feature to add controls for pause, zoom, pan, etc. Unfortunately, the latter debug controls get in the way of recording the video, and appear in the recording.

When a user has clicked Record or (after #848) taking a snapshot, the debug controls should be automatically disabled. This means the Haskell code needs to listen for some kind of signal from the environment to disable that behavior.

Trace the Haskell code responsible for the on-hover pause, zoom, and pan controls and the environment's recording or snapshot signals, including the context of issue #848. Determine how recording state reaches the program, then make the controls disappear while recording or taking a snapshot and verify that they return afterward.

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