Fix LMB hold when hovering with tablet pen

[YNataniel295]

Fixes an issue where LMB would be released immediately when the pen is in hover range. Added pen pressure hysteresis, may be needed.

Here are links to the reported issues.
https://osu.ppy.sh/community/forums/topics/2089384
ppy/osu#27310

[peppy]

Is this the kind of thing we can hard-code instead? I feel like we should be able to come up with a pretty good value which will work for 99.999% of users.

[YNataniel295]

The game already has a pressure threshold slider. Maybe we should add a similar pressure hysteresis slider for user customization or add it as an experimental feature? Maybe set the default value to 0.05 or leave it at 0 to not change the existing logic.

In the current version, the pen always sends the LMB state. Is this to prevent hangs in the held state, or is there another reason?

[YNataniel295]

I removed the public PressureHysteresis setting / API and hard-coded a small internal hysteresis band (0.05) to avoid chatter around the existing PressureThreshold. Main fix remains: only enqueue pen button state on changes, plus explicit release when tablet disappears.