Use PreciseY for scrolling and remove duplicated injectmousemove call

Closes #9134 (closed) and !5344 (merged)

@nox7 basically co-author. Also Claude. Idea conversion.

• I have read the CONTRIBUTING guidelines
• My code runs locally
• My code passes CI on my fork (it is chugging)

Question: Is the duped code line that is very old/from Scrawl 09e93319 still important? Looks like it was for an ancient controller issue (#3978 (closed)). I don't have a gamepad/controller I can quickly setup for testing.

For macOS users/trackpad users:

• Can you scroll in the scripts menu with lots of scripts? Can you reverse scrolling direction and it works?
• If pulling down = up for you, does the scrolling honor the inverted scrolling direction? Vice versa?
• Does scrolling on the map do anything? (I don't know how it is supposed to work, it does do...something)
• Does Stat Window Extender scroll bar work (it didn't before)?
• Can you still scroll 3rd person POV?