[berlin-566]

Summary

This PR addresses auto-hide screen space reclamation and introduces a new expandable Applets dropdown and configuration engine in the Settings UI with 5 key applets and bar glassmorphism controls.

1. Auto-Hide Window Area Reclamation

• Configured layer-shell exclusion mode dynamically: when SettingsService.barAutoHide is enabled for Pill/Island bar modes, barSurface sets WlrLayershell.exclusionMode: ExclusionMode.Ignore.
• Windows now utilize the complete screen height to the top monitor bezel instead of leaving an empty unused gap.
• When revealed on mouse hover, the bar glides smoothly over the window as a true floating overlay with exact capsule input masking, preventing layout bounce or window resizing stutter.

2. Settings Sidebar "Applets" Dropdown Submenu

• Updated SettingsSidebar.qml to turn Desktop Bar into an expandable parent row featuring a smooth rotate chevron.
• Clicking Desktop Bar expands an indented child nav item named Applets (tab: 9) with fluid slide animations.
• Added full metadata, navigation order, and shortcut support in Settings.qml.

3. Comprehensive Bar Applets & Features

• Active Window Title & Icon Pill (ActiveWindowPill.qml):
  • Compositor-agnostic focused application tracking (Niri IPC focused-window & Hyprland).
  • Displays application icon with truncated title ([App] Title).
  • Left-click: toggles maximize / restore (maximize-column / fullscreen 1).
  • Right-click / double-click: invokes application switcher (launcher overview).
• Dynamic Audio Visualizer & Mini Media Pill (MediaButton.qml):
  • 4-bar bouncing Cava audio visualizer synchronized to system sound output.
  • Spring-scale expansion animation whenever songs change.
  • Hover playback controls (previous, play/pause, next) directly in the pill.
• Weather Pill & 3-Day Forecast Card (WeatherPill.qml, WeatherCard.qml, WeatherService.qml):
  • Displays condition icon + temperature (e.g., ☀ 33°C / 91°F) beside the clock.
  • Clicking opens an anchored floating popout card showing current humidity, wind speed, feels-like, and 3-day forecast with duotone weather icons.
  • Powered by Open-Meteo with local disk caching and 15-minute polling.
• Battery Health & Charge Estimator (BatteryPill.qml):
  • Dynamic battery capsule with level percentage and charge/discharge time estimation (e.g. ⚡ 85% • 3h 15m).
  • Subtle breathing pulse animation when actively charging.
• Network Traffic Monitor & Do Not Disturb Pills (NetworkPill.qml, DndPill.qml):
  • Real-time download/upload speed indicator (e.g. ↓ 1.2M ↑ 85K) from /proc/net/dev.
  • 1-click Do Not Disturb bell toggle that silences notification banners.
• Bar Translucency & Glassmorphism:
  • Segmented style selector: Solid Background, Frosted Glass (blur), Translucent Gradient, or Wallpaper-adaptive tint.
  • Opacity & blur strength slider (20%–100%) in Bar Applets settings.