[FR]: Mesh Readout Grid Size configurability

Context:

I use a Snapmaker A350. My bed is a 350mm X 350mm bed. The Snapmaker has the ability to do an auto-bed leveling in a 5x5, 4x4 or 3x3 grid. (Also uses Marlin Firmware)

Frustration:

While the coordinate system used in the visualization plugin is true to the bed dimensions, it still requires some mental translation to know which X/Y grid coordinates to use with an M421 adjustment command.

What would be awesome:

Instead of giving the X/Y coordinate values in the context of the bed dimensions, I would love to see the X/Y coordinates in the range of the calibration grid size.

Example:

Bed calibration done with a 5x5 grid
with a 350mm x 350mm bed, the M421 command to address the center of the bed (0,0 being front-left with a center X/Y coordinate set being 175/175) would be M421 I2 J2.
If the value at that center point is, say 0.125mm above 0, I would issue a M421 I2 J2 Q-0.125 command.

Feature:

Allow the user to define the grid size that the visualization reads out when hovering over the visualization itself. You would see tooltips that could (on the ULTRA convenient end) look like M421 I2 J2 Q-0.125 and on the low-end side look like X (i): 2, Y (j): 2, Z (Q): 0.125

jneilliii / OctoPrint-BedLevelVisualizer