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/clock/Panel.qml

@@ -67,10 +67,8 @@ Panel {
   // convention. Clicking the grid's "W" heading writes the choice back to
   // shell.json.
   readonly property int weekStart: Model.normalizedWeekStart(setting("weekStartDay", null), Qt.locale().firstDayOfWeek)
-  // The interface is English throughout, so day names are not taken from the
-  // system locale. Where the week starts still is: that is a regional
-  // convention rather than a translation, and it stays overridable above.
-  readonly property var labelLocale: Qt.locale("en_US")
+  // Day names follow the interface language, not the system locale; the week start above is a regional convention.
+  readonly property var labelLocale: I18n.chinese ? Qt.locale("zh_CN") : Qt.locale("en_US")
   readonly property string nextWeekStartLabel: labelLocale.dayName(Model.toggledWeekStart(weekStart), Locale.LongFormat)
   readonly property var weekdays: Model.weekdayOrder(weekStart)
   readonly property var weeks: Model.monthGrid(viewYear, viewMonth, weekStart, todayKey)
@@ -318,7 +316,7 @@ Panel {
                 id: heroDate
                 textFormat: Text.PlainText
                 anchors.verticalCenter: parent.verticalCenter
-                text: Qt.formatDate(root.today, "MMMM d")
+                text: I18n.chinese ? root.labelLocale.toString(root.today, "M月d日") : Qt.formatDate(root.today, "MMMM d")
                 color: heroMouse.containsMouse
                   ? Style.hoverStateColor(root.contentForeground, Commons.Color.accent)
                   : root.contentForeground
@@ -341,7 +339,7 @@ Panel {
 
               PanelToolTip {
                 visible: heroMouse.containsMouse
-                text: "Back to today"
+                text: I18n.tr("Back to today")
                 fontFamily: root.contentFontFamily
               }
             }
@@ -374,7 +372,8 @@ Panel {
 
                 Text {
                   anchors.verticalCenter: parent.verticalCenter
-                  text: "BORN"
+                  textFormat: Text.PlainText
+                  text: I18n.tr("BORN")
                   color: Qt.darker(root.contentForeground, 1.5)
                   font.family: root.contentFontFamily
                   font.pixelSize: Style.font.bodySmall
@@ -385,7 +384,7 @@ Panel {
                   id: bornField
                   width: Style.space(70)
                   anchors.verticalCenter: parent.verticalCenter
-                  placeholderText: "year"
+                  placeholderText: I18n.tr("year")
                   foreground: root.contentForeground
                   font.family: root.contentFontFamily
                   inputMethodHints: Qt.ImhDigitsOnly
@@ -397,7 +396,8 @@ Panel {
                   anchors.verticalCenter: parent.verticalCenter
                   anchors.verticalCenterOffset: 0
                   leftPadding: Style.space(6)
-                  text: "LIVE TO"
+                  textFormat: Text.PlainText
+                  text: I18n.tr("LIVE TO")
                   color: Qt.darker(root.contentForeground, 1.5)
                   font.family: root.contentFontFamily
                   font.pixelSize: Style.font.bodySmall
@@ -484,7 +484,8 @@ Panel {
                 id: lifeLabel
                 anchors.left: parent.left
                 anchors.verticalCenter: parent.verticalCenter
-                text: "LIFE"
+                textFormat: Text.PlainText
+                text: I18n.tr("LIFE")
                 color: Qt.darker(root.contentForeground, 1.5)
                 font.family: root.contentFontFamily
                 font.pixelSize: Style.font.bodySmall
@@ -603,7 +604,7 @@ Panel {
 
                   PanelToolTip {
                     visible: weekStartMouse.containsMouse
-                    text: "Start weeks on " + root.nextWeekStartLabel
+                    text: I18n.tr("Start weeks on %1", root.nextWeekStartLabel)
                     fontFamily: root.contentFontFamily
                   }
                 }
@@ -726,7 +727,7 @@ Panel {
                 // "MAY 2026" and a "SEPTEMBER 2026".
                 width: Style.space(130)
                 horizontalAlignment: Text.AlignHCenter
-                text: Qt.formatDate(root.viewDate, "MMMM yyyy").toUpperCase()
+                text: I18n.chinese ? root.labelLocale.toString(root.viewDate, "yyyy年M月") : Qt.formatDate(root.viewDate, "MMMM yyyy").toUpperCase()
                 color: Qt.darker(root.contentForeground, 1.4)
                 font.family: root.contentFontFamily
                 font.pixelSize: Style.font.body
@@ -740,7 +741,7 @@ Panel {
                 anchors.leftMargin: -Style.space(8)
                 anchors.verticalCenter: parent.verticalCenter
                 iconText: "󰅁"
-                tooltipText: "Previous month"
+                tooltipText: I18n.tr("Previous month")
                 foreground: root.contentForeground
                 fontFamily: root.contentFontFamily
                 onClicked: root.moveMonth(-1)
@@ -751,7 +752,7 @@ Panel {
                 anchors.rightMargin: -Style.space(8)
                 anchors.verticalCenter: parent.verticalCenter
                 iconText: "󰅂"
-                tooltipText: "Next month"
+                tooltipText: I18n.tr("Next month")
                 foreground: root.contentForeground
                 fontFamily: root.contentFontFamily
                 onClicked: root.moveMonth(1)