fix: refresh macOS display bounds on hotplug

[grazzolini]

Summary

• Recompute macOS capture bounds from the current active-display union after monitor changes.
• Refresh bounds during pointer motion when Quartz callbacks are missed or arrive before topology settles.
• Reanchor an active capture to the updated edge while preserving and clamping the cross-axis position.

Testing

• cargo fmt --check
• cargo test -p input-capture
• cargo clippy -p input-capture --all-targets
• Manually switched the left external display from macOS to Linux and crossed from the new macOS left edge without restarting Lan Mouse.

[grazzolini]

I have been using this patch for a couple of months and it works. This has been tested with 3 monitors and many combinations among them, including changing the geometry a lot.