Add modular interactive widgets to the Quickshell bar

Introduces a widgets/ directory of first-party QML modules and a common/
helpers library. Widgets auto-load by name from
default/quickshell/bar/widgets/<name>.qml — no edits to shell.qml needed
for additions beyond the firstPartyWidgets registry.

New widgets (all orientation-aware, top/bottom/left/right):
- media: MPRIS now-playing with scrolling label, cover art popup,
  play/pause/skip controls
- audioPanel: master volume slider, output device picker, per-app mixer
- networkPanel: Wi-Fi scan + connect, current connection details
- bluetoothPanel: paired device list, connect/disconnect, battery
- calendar: month grid popup keyed to today
- notificationCenter: live notification feed, DND toggle, clear all
- brightness: slider popup with scroll-to-adjust
- powerProfile: power-saver/balanced/performance picker (UPower)
- systemStats: inline CPU + RAM sparklines, expanded popup with btop
- weatherFlyout: weather popup with refresh and full report
- workspacesPro: animated focus indicator that slides between workspaces
- powerMenu: lock/suspend/log out/reboot/shutdown popup
- idleInhibitor: coffee-cup toggle wired to omarchy-toggle-idle
- microphone: mic state + mute toggle + scroll volume

Common helpers (default/quickshell/bar/common/):
- WidgetButton: hover/press scale animation, tooltip integration
- PopupCard: orientation-aware anchor + slide-in opacity transition
- Slider: drag/wheel-able linear slider with knob hover bump
- PillButton: rounded action button with icon + label

Bar root gains requestPopout/releasePopout so only one popup is open at
a time across widgets.

Updates bar-defaults.json to ship the new widgets out of the box while
keeping the legacy modules available.

default/quickshell/bar/widgets/idleInhibitor.qml

@@ -0,0 +1,66 @@
+import QtQuick
+import Quickshell
+import Quickshell.Io
+import "../common" as Common
+
+Item {
+  id: root
+
+  property QtObject bar: null
+  property string moduleName: "idleInhibitor"
+  property var settings: ({})
+
+  property bool active: false
+  property int holdSeconds: 0
+
+  readonly property string icon: active ? "󰛊" : "󰾪"
+
+  function refresh() {
+    if (!statusProc.running) statusProc.running = true
+  }
+
+  function toggle() {
+    if (root.bar) root.bar.run("omarchy-toggle-idle")
+    refreshTimer.restart()
+  }
+
+  Component.onCompleted: refresh()
+
+  Process {
+    id: statusProc
+    command: ["bash", "-lc", "if pgrep -x hyprlock >/dev/null 2>&1; then echo locked; elif pgrep -f 'systemd-inhibit' >/dev/null 2>&1; then echo inhibited; elif [[ -f /tmp/omarchy-idle-off ]]; then echo off; else echo idle; fi"]
+    stdout: StdioCollector {
+      waitForEnd: true
+      onStreamFinished: {
+        var state = String(text || "").trim()
+        root.active = state === "inhibited" || state === "off"
+      }
+    }
+  }
+
+  Timer {
+    id: refreshTimer
+    interval: 1500
+    onTriggered: root.refresh()
+  }
+
+  Timer {
+    interval: 5000
+    running: true
+    repeat: true
+    onTriggered: root.refresh()
+  }
+
+  implicitWidth: button.implicitWidth
+  implicitHeight: button.implicitHeight
+
+  Common.WidgetButton {
+    id: button
+    anchors.fill: parent
+    bar: root.bar
+    text: root.icon
+    active: root.active
+    tooltipText: root.active ? "Idle inhibited — click to allow sleep" : "System can idle — click to keep awake"
+    onPressed: function() { root.toggle() }
+  }
+}