fix(windows): make portal geometry per-monitor DPI aware

[s-qin]

fix(windows): make portal geometry per-monitor DPI aware

Problem

OpenSpan mixed logical and physical coordinates on mixed-DPI Windows displays.

Reproduction

Real physical desktop: left monitor 1600x2560, PRIMARY 1920x1080, right monitor 2560x1600.

OpenSpan before the fix enumerated: 800x1280 / 1536x864 (PRIMARY) / 1280x800 — DPI-virtualized logical values.

Observed effect: the portal captured the mouse before the physical screen edge — premature capture while the cursor was still above the true bottom edge of the PRIMARY monitor.

Root cause

No Windows OpenSpan process ever declared DPI awareness. The GUI / setup / portal processes ran as DPI-unaware (or system-aware), so monitor rectangles (GetMonitorInfoW in win/openspan_setup.py), the portal edge geometry (written into openspan_config.json by the GUI) and low-level-hook cursor coordinates ended up in DPI-virtualized coordinate spaces (e.g. primary reported 1536x864 instead of 1920x1080). Portal edges were therefore crossed early.

Fix

• New win/dpi_aware.py: declares per-monitor DPI awareness V2 first (SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2)), with fallbacks (shcore SetProcessDpiAwareness(PROCESS_PER_MONITOR_DPI_AWARE), then user32 SetProcessDPIAware), and reports the awareness actually in force via GetProcessDpiAwareness.
• Called from every Windows process before any Tk window / monitor / hook API: openspan_setup.py (GUI + setup role), openspan_portal.py, openspan_launcher.py.
• Result: monitor rectangles, cursor / low-level hook coordinates and portal edge geometry all live in one physical-pixel coordinate space. Nothing hardcoded — any monitor layout stays dynamic, mixed-DPI included.

Validation

Manually tested on real hardware (mixed-DPI, three displays):

• GUI enumerates 1600x2560 / 1920x1080 (PRIMARY) / 2560x1600
• no premature capture in non-portal areas
• portal entry from the PRIMARY bottom edge into the iPad
• crossing back from the iPad edge returns control to Windows
• Esc x3 panic bail still works

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