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/bluetoothPanel.qml

@@ -0,0 +1,152 @@
+import QtQuick
+import Quickshell
+import Quickshell.Bluetooth
+import "../common" as Common
+
+Item {
+  id: root
+
+  property QtObject bar: null
+  property string moduleName: "bluetoothPanel"
+  property var settings: ({})
+
+  property bool popupOpen: false
+
+  function closePopout() { popupOpen = false }
+
+  readonly property var adapter: Bluetooth.defaultAdapter
+  readonly property var devices: Bluetooth.devices ? Bluetooth.devices.values : []
+
+  readonly property var connectedDevices: {
+    var list = []
+    for (var i = 0; i < devices.length; i++)
+      if (devices[i] && devices[i].connected) list.push(devices[i])
+    return list
+  }
+
+  readonly property var knownDevices: {
+    var list = []
+    for (var i = 0; i < devices.length; i++) {
+      var d = devices[i]
+      if (d && (d.paired || d.connected || d.bonded || d.trusted)) list.push(d)
+    }
+    list.sort(function(a, b) {
+      if (a.connected !== b.connected) return a.connected ? -1 : 1
+      return (a.name || a.deviceName || "").localeCompare(b.name || b.deviceName || "")
+    })
+    return list
+  }
+
+  readonly property string icon: {
+    if (!adapter) return ""
+    if (!adapter.enabled) return "󰂲"
+    if (connectedDevices.length > 0) return "󰂱"
+    return ""
+  }
+
+  visible: adapter !== null
+  implicitWidth: button.implicitWidth
+  implicitHeight: button.implicitHeight
+
+  Common.WidgetButton {
+    id: button
+    anchors.fill: parent
+    bar: root.bar
+    text: root.icon
+    horizontalMargin: 8.5
+    tooltipText: root.adapter ? (root.adapter.enabled ? "Bluetooth: " + root.connectedDevices.length + " connected" : "Bluetooth off") : ""
+
+    onPressed: function(b) {
+      if (b === Qt.RightButton && root.adapter) root.adapter.enabled = !root.adapter.enabled
+      else if (b === Qt.MiddleButton) root.bar.run("omarchy-launch-bluetooth")
+      else root.popupOpen = !root.popupOpen
+    }
+  }
+
+  Common.PopupCard {
+    anchorItem: button
+    owner: root
+    bar: root.bar
+    open: root.popupOpen
+    contentWidth: 320
+    contentHeight: column.implicitHeight + 28
+
+    Column {
+      id: column
+      anchors.fill: parent
+      spacing: 8
+
+      Row {
+        width: parent.width
+        spacing: 8
+
+        Text {
+          text: "Bluetooth"
+          color: root.bar.foreground
+          font.family: root.bar.fontFamily
+          font.pixelSize: 13
+          font.bold: true
+          anchors.verticalCenter: parent.verticalCenter
+        }
+
+        Item { width: parent.width - 200; height: 1 }
+
+        Common.PillButton {
+          iconText: root.adapter && root.adapter.enabled ? "" : ""
+          text: root.adapter && root.adapter.enabled ? "On" : "Off"
+          foreground: root.bar.foreground
+          horizontalPadding: 8
+          verticalPadding: 4
+          active: root.adapter && root.adapter.enabled
+          onClicked: if (root.adapter) root.adapter.enabled = !root.adapter.enabled
+        }
+
+        Common.PillButton {
+          iconText: ""
+          foreground: root.bar.foreground
+          horizontalPadding: 8
+          verticalPadding: 4
+          enabled: root.adapter !== null && root.adapter.enabled
+          opacity: enabled ? 1 : 0.4
+          active: root.adapter && root.adapter.discovering
+          onClicked: if (root.adapter) root.adapter.discovering = !root.adapter.discovering
+        }
+      }
+
+      Repeater {
+        model: root.knownDevices
+
+        Common.PillButton {
+          required property var modelData
+
+          width: parent.width
+          iconText: modelData && modelData.connected ? "󰂱" : ""
+          text: {
+            var label = modelData ? (modelData.deviceName || modelData.name || modelData.address || "Device") : ""
+            if (modelData && modelData.batteryAvailable) label += "  " + Math.round(modelData.battery * 100) + "%"
+            return label
+          }
+          foreground: root.bar.foreground
+          horizontalPadding: 10
+          verticalPadding: 6
+          active: modelData && modelData.connected
+
+          onClicked: {
+            if (!modelData) return
+            if (modelData.connected) modelData.disconnect()
+            else modelData.connect()
+          }
+          onRightClicked: if (modelData) modelData.forget()
+        }
+      }
+
+      Text {
+        visible: root.knownDevices.length === 0
+        text: root.adapter && root.adapter.enabled ? "Scanning for devices…" : "Turn Bluetooth on to scan"
+        color: Qt.darker(root.bar.foreground, 1.5)
+        font.family: root.bar.fontFamily
+        font.pixelSize: 11
+      }
+    }
+  }
+}