feat(shell): implement unified popout manager, pill anchoring, and fast IPC

[Chintanpatel24]

Summary

Transforms Agility Shell from disjointed floating popups into a cohesive, fluid Wayland desktop shell inspired by DankMaterialShell (DMS).

Core Changes

1. Unified Popout Surface & Fluid Pill Anchoring (snippets/popout_manager.py):

   • Replaced fragmented, per-widget AppletWindow instances with a single persistent Wayland LayerShell surface per bar (UnifiedPopoutManager).
   • Smooth Pill Tracking: Moving or clicking between bar pills calculates the exact pill center and glides the popout horizontally across the screen via 60fps cubic ease-out interpolation (1 - (1 - t)³).
   • In-Place View Cross-Fading: Content inside the card transitions smoothly inside a hardware-accelerated crossfade stack without window recreation, tearing, or Cairo snapshot lag.
   • Active Pill Bonding (.bar-widget.active-popout): The active trigger pill illuminates with accent color and elevation glow, visually tethering the bar pill to the popout sheet.
   • Desktop Dimming Scrim (.desktop-scrim): A soft semi-transparent dimming scrim focuses user attention onto the open popout and dismisses it cleanly on any outside click.

2. Bar & Menu Integration (bar.py):

   • Initialized popout_manager on each active Bar.
   • Wired WidgetWrapper and GroupWrapper clicks and hover transitions directly into the unified manager.
   • Updated BarManager.toggle() so CLI triggers and compositor shortcuts route directly through the popout manager.

3. Spotlight Launcher Intelligence (windows/launcher.py, style/launcher.css):

   • Added LauncherActionItem supporting instant action triggers:
     • Inline Math (= 15 * 8): Evaluates arithmetic in real time; hitting Enter copies the answer directly to clipboard.
     • Shell Commands (> btop or > kitty): Instant command execution directly from the search bar.

4. Fast Shell CLI & Compositor Synergy (bin/agl, config/niri.kdl):

   • Added dedicated agl subcommands:
     • agl volume <up|down|mute>: Adjusts audio and triggers the OSD overlay.
     • agl brightness <up|down>: Adjusts display brightness and triggers the OSD overlay.
     • agl launcher: Instant trigger for the Spotlight launcher.
     • agl cc: Instant trigger for Control Center / Quick Settings.
     • agl toggle <key>: Seamlessly opens/slides to any applet (audio, wifi, bluetooth, calendar, weather, media).
   • Standardized config/niri.kdl keybindings on agl subcommands for audio, brightness, launcher, and control center.

Verification

• Verified Python bytecode compilation: python3 -m compileall -q . exited with 0 errors.
• Verified bash syntax: bash -n bin/agl exited with 0 errors.

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[Chintanpatel24]

seems fine , but not looks fine - not able to merge yet - need fixes