Replaces the boolean "Force VBI to 90 Hz" override with an explicit
choice across Off / Auto / 72 / 90 / 120 Hz. Auto samples the headset
refresh rate at OpenXR session startup (via XR_FB_display_refresh_rate)
and rounds to the closest supported value. Migrates the legacy
AutoVBIFromHMD setting on first load. Per-game profile editor and the
HK_VR_TOGGLE_FORCE_VBI hotkey are updated to cycle Off <-> Auto.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
iChris4