feat: add selection tolerance

[Sidharth-Singh10]

Closes #2141
Modified the check_layer function in the document_message_handler to add tolerance-based selection

issue2141.mp4

[Keavon]

!build

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[Keavon]

It looks like you're using the bounding box rather than actual proximity to the path. That causes paths like this (which have no Fill node) to be selectable from far too generous of a distance, because anywhere within its bounding box makes it accept the selection.

Please note, we already have a logic for extending the selection to some slightler-larger-than-1.0 scale factor of the shape's stroke thickness. Notice how you can inflate the stroke and it becomes easy to select, even a bit beyond its stroke. I think the proper solution here is to discard your current approach and actually just modify that scale factor: use exactly 1.0 for large values (as measured in viewport space) and cap it to a minimum thickness for smaller values (as measured in viewport space) to ensure no line's click target becomes less thick than some minimum.