Add Simplified Chinese as a system language

The installer asks for the language before the keyboard, and
Setup > Language (omarchy language en|zh) switches it later. Under
zh_CN the menu reads its labels from omarchy-menu.zh-cn.jsonc, the
shell from I18nZh.js through I18n.tr, and notifications are worded
by their sender through omarchy-text, which reads the same table.
User text is never translated.

shell/plugins/panels/bluetooth/Panel.qml

@@ -65,19 +65,19 @@ Panel {
 
   property int phraseIndex: 0
   readonly property var activePhrases: [
-    "Untangling wires",
-    "Streaming vikings",
-    "Pairing mysteries",
-    "Herding headsets",
-    "Taming radios",
-    "Summoning speakers",
-    "Wrangling codecs",
-    "Polishing packets"
+    I18n.tr("Untangling wires"),
+    I18n.tr("Streaming vikings"),
+    I18n.tr("Pairing mysteries"),
+    I18n.tr("Herding headsets"),
+    I18n.tr("Taming radios"),
+    I18n.tr("Summoning speakers"),
+    I18n.tr("Wrangling codecs"),
+    I18n.tr("Polishing packets")
   ]
   readonly property bool rotatingPhrases: adapter && adapter.enabled
   readonly property string heroStatusText: {
-    if (!adapter) return "No adapter"
-    if (!adapter.enabled) return "Turned Off"
+    if (!adapter) return I18n.tr("No adapter")
+    if (!adapter.enabled) return I18n.tr("Turned Off")
     return activePhrases[phraseIndex % activePhrases.length]
   }
 
@@ -102,7 +102,7 @@ Panel {
   // sits above the device sections so the adapter can be toggled by keyboard
   // even when it is off and no device rows exist.
   readonly property bool headerHasCursor: cursorActive && focusSection === "header"
-  readonly property string toggleHint: root.adapter && root.adapter.enabled ? "Turn Bluetooth off" : "Turn Bluetooth on"
+  readonly property string toggleHint: root.adapter && root.adapter.enabled ? I18n.tr("Turn Bluetooth off") : I18n.tr("Turn Bluetooth on")
 
   readonly property color hoverFill: bar
     ? Style.hoverFillFor(bar.foreground, Commons.Color.accent)
@@ -184,7 +184,7 @@ Panel {
     var rows = scrollRows
     if (index < 0 || index >= rows.length) return ""
     if (index > 0 && rows[index - 1].section === rows[index].section) return ""
-    return rows[index].section === "known" ? "PAIRED" : "AVAILABLE"
+    return rows[index].section === "known" ? I18n.tr("PAIRED") : I18n.tr("AVAILABLE")
   }
 
   function audioSinks() {
@@ -739,7 +739,8 @@ Panel {
             spacing: Style.space(2)
 
             Text {
-              text: "Bluetooth"
+              textFormat: Text.PlainText
+              text: I18n.tr("Bluetooth")
               color: root.bar.foreground
               font.family: root.bar.fontFamily
               font.pixelSize: Style.font.title
@@ -776,7 +777,7 @@ Panel {
           spacing: Style.space(10)
 
           PanelSectionHeader {
-            text: "CONNECTED"
+            text: I18n.tr("CONNECTED")
             foreground: root.bar.foreground
             fontFamily: root.bar.fontFamily
           }
@@ -868,9 +869,9 @@ Panel {
         Text {
           textFormat: Text.PlainText
           visible: root.connectedDevices.length === 0 && root.scrollRows.length === 0
-          text: !root.adapter ? "No Bluetooth adapter"
-              : !root.adapter.enabled ? "Turn Bluetooth on to scan"
-              : "Scanning for devices…"
+          text: !root.adapter ? I18n.tr("No Bluetooth adapter")
+              : !root.adapter.enabled ? I18n.tr("Turn Bluetooth on to scan")
+              : I18n.tr("Scanning for devices…")
           color: Qt.darker(root.bar.foreground, 1.5)
           font.family: root.bar.fontFamily
           font.pixelSize: Style.font.bodySmall
@@ -895,9 +896,9 @@ Panel {
     readonly property string action: root.pendingAction(dev ? dev.address : "")
     readonly property string actionTooltip: {
       if (!dev) return ""
-      if (isConnected) return "Disconnect"
-      if (isDiscovered) return "Pair"
-      return "Connect"
+      if (isConnected) return I18n.tr("Disconnect")
+      if (isDiscovered) return I18n.tr("Pair")
+      return I18n.tr("Connect")
     }
 
     readonly property bool rowSelected: root.cursorActive && root.focusSection === sectionName && root.selectedIndex === rowIndex
@@ -912,13 +913,13 @@ Panel {
 
     readonly property string statusText: {
       if (!dev) return ""
-      if (action === "forgetting") return "Forgetting…"
-      if (action === "disconnecting" || devState === 2) return "Disconnecting…"
+      if (action === "forgetting") return I18n.tr("Forgetting…")
+      if (action === "disconnecting" || devState === 2) return I18n.tr("Disconnecting…")
       if (isConnected) {
         if (dev.batteryAvailable) return Math.round(dev.battery * 100) + "%"
-        return sectionName === "connected" ? "" : "Connected"
+        return sectionName === "connected" ? "" : I18n.tr("Connected")
       }
-      if (action === "connecting" || devState === 3 || dev.pairing === true) return "Connecting…"
+      if (action === "connecting" || devState === 3 || dev.pairing === true) return I18n.tr("Connecting…")
       if (isDiscovered) return ""
       return ""
     }
@@ -995,7 +996,7 @@ Panel {
 
         Text {
           textFormat: Text.PlainText
-          text: root.deviceLabel(row.dev) || "Device"
+          text: root.deviceLabel(row.dev) || I18n.tr("Device")
           color: root.bar.foreground
           font.family: root.bar.fontFamily
           font.pixelSize: Style.font.body
@@ -1020,7 +1021,7 @@ Panel {
         anchors.verticalCenter: parent.verticalCenter
         visible: row.showForgetButton
         iconText: "󰅙"
-        tooltipText: "Forget"
+        tooltipText: I18n.tr("Forget")
         foreground: root.bar.foreground
         hoverColor: root.bar.foreground
         fontFamily: root.bar.fontFamily