feature: real-time pattern visualization (someday/maybe)

[nnirror]

• consider adding a UI to the text editor to visualize patterns that are currently playing.
• consider adding key commands to stop and/or clear pattern(s), similar to the key command that runs patterns.

[nnirror]

this commit addresses the second item, key commands for stopping and keeping patterns: aea70be

keeping this open to potentially address pattern visualization