Add native-style Liquid Glass OSD HUD for macOS 26 and 27 - #1931

Summary

In macOS 26/27 (Tahoe+), the private OSDUIHelper XPC service no longer displays the legacy chiclet HUD when OSDManager.sharedManager().showImage(...) is called. As a result, adjusting brightness, contrast, or volume on external displays via MonitorControl produces no on-screen feedback.

This PR introduces a native macOS 26+ Liquid Glass On-Screen Display HUD (MacOS27OSDHudController, OSDHudPanel, MacOS27OSDHudView) in OSDUtils.swift while preserving the legacy OSDManager path for macOS 15 and earlier.

What's Changed

• Native NSGlassEffectView Banner Pill (292 × 63 pt, cornerRadius = 19.5):
  • Uses the adaptive SystemBanner glass variant (_variant = 9 / notificationCenter material at 63 pt height) so the backdrop preserves wallpaper color saturation and renders the native luminous specular rim.
  • Displays the friendly display name (Display.getFriendlyName()), a pill badge (56%, 56% • 280 nits when nits calibration is available, or Locked), min/max SF Symbols (sun.min.fill/sun.max.fill, speaker.fill/speaker.wave.3.fill, circle.lefthalf.filled/circle.righthalf.filled), a continuous progress bar, and 16 chiclet tick dots.
• Active Glass Rim on Non-Activating NSPanel:
  • Overrides hasKeyAppearance, _hasActiveAppearance, and _hasActiveControls on the borderless .nonactivatingPanel with hasShadow = false so NSGlassEffectView renders its luminous specular glass border without stealing focus from the active app or drawing a dark rectangular window shadow.
• Real-Time Backdrop Luminance Adaptation, Reduce Motion, and VoiceOver Accessibility:
  • Uses a WindowServer-aware CABackdropLayer (tracksLuma = true) with hysteresis (0.45 / 0.53) to sample the real-time luminance behind the HUD pill and automatically flip the glass appearance and foreground colors (.darkAqua vs. .aqua), preventing dark-on-dark or white-on-white text regardless of the system Light/Dark mode setting.
  • Respects NSWorkspace.shared.accessibilityDisplayShouldReduceMotion to skip fade animations when Reduce Motion is enabled.
  • Exposes .levelIndicator accessibility role, display title label, and percentage/nits value on the track bar for VoiceOver.
• Multi-Display & Hardware/Software Control Routing:
  • Adds DisplayManager.resolveEffectiveDisplayID(_:) and routes OSD calls through the effective display ID so virtual/software-dimmed displays resolve to their physical screen.

Screenshots

Dark Green Backdrop (luma = 0.27 → .darkAqua)	Light Green Backdrop (luma = 0.78 → .aqua)

Dark Backdrop in Light Mode (luma = 0.12 → .darkAqua)	Light Backdrop in Dark Mode (luma = 0.95 → .aqua)