Address momus review: fix icons, vertical layout, popup coordination

- Replace nerd font glyphs that were stripped during the initial widget
  writes with verified codepoints sourced from the JetBrains Mono Nerd
  Font cmap (cpu-64-bit, scale-balance, notification-clear-all, etc).
- systemStats now switches to a Column layout when the bar is vertical
  so the widget no longer overflows a 28px-wide side bar.
- Remove notificationCenter from defaults: it registers a notification
  server and would collide with the mako daemon Omarchy autostarts.
- PopupCard owns the popout coordinator lifecycle and delegates close to
  its widget owner when provided; calendar and media now pass owner.
- brightness debounces brightnessctl writes through a coalescing timer
  to avoid spawning a process per slider tick.
- audioPanel tracks unfiltered Pipewire sinks/streams via PwObjectTracker
  so audio metadata becomes available before filtering.
- ModuleSlot re-injects bar/moduleName/settings whenever the bar config
  serial changes so widget settings update live with bar.json.
- Guard null bar references in workspacesPro and systemStats components
  that are constructed before bar injection.

default/quickshell/bar/bar-defaults.json

@@ -4,8 +4,8 @@
   "centerAnchor": "calendar",
   "layout": {
     "left": ["omarchy", "workspacesPro"],
-    "center": ["media", "calendar", "weatherFlyout", "update", "voxtype", "screenRecording", "idle"],
-    "right": ["tray", "systemStats", "notificationCenter", "microphone", "bluetoothPanel", "networkPanel", "audioPanel", "brightness", "powerProfile", "battery", "powerMenu"]
+    "center": ["media", "calendar", "weatherFlyout", "update", "voxtype", "screenRecording", "idle", "notifications"],
+    "right": ["tray", "systemStats", "microphone", "bluetoothPanel", "networkPanel", "audioPanel", "brightness", "powerProfile", "battery", "powerMenu"]
   },
   "modules": {
     "calendar": {