Use Color.foreground / Style.font.family for fallbacks

Five sites hardcoded "#cacccc" or "JetBrainsMono Nerd Font" as the
fallback when no bar context was available. Those magic strings are
the *current* palette defaults — they diverge silently when the theme
changes. Bind to the Color / Style singletons so the fallback tracks
whatever the theme says the foreground / monospace family should be.

Color.qml itself keeps the literal "#cacccc" — that's the seed value
the singleton is bootstrapped with before the theme loads.

shell/plugins/bar/widgets/activeWindow.qml

@@ -33,8 +33,8 @@ BarWidget {
       anchors.left: parent.left
       width: parent.width
       text: root.title
-      color: root.bar ? root.bar.foreground : "#cacccc"
-      font.family: root.bar ? root.bar.fontFamily : "JetBrainsMono Nerd Font"
+      color: root.bar ? root.bar.foreground : Color.foreground
+      font.family: root.bar ? root.bar.fontFamily : Style.font.family
       font.pixelSize: Style.font.body
       elide: Text.ElideRight
       opacity: 0.85

shell/plugins/bar/widgets/lockKeys.qml

@@ -87,8 +87,8 @@ BarWidget {
     property bool active: false
 
     text: glyph
-    color: active ? (root.bar ? root.bar.foreground : "#cacccc") : Qt.rgba(0.7, 0.7, 0.7, 0.3)
-    font.family: root.bar ? root.bar.fontFamily : "JetBrainsMono Nerd Font"
+    color: active ? (root.bar ? root.bar.foreground : Color.foreground) : Qt.rgba(0.7, 0.7, 0.7, 0.3)
+    font.family: root.bar ? root.bar.fontFamily : Style.font.family
     font.pixelSize: Style.font.bodySmall
   }
 }

shell/plugins/bar/widgets/systemStats.qml

@@ -233,8 +233,8 @@ BarWidget {
     property string title: ""
     property string value: ""
     property var history: []
-    property color barFg: "#cacccc"
-    property string fontFamily: "JetBrainsMono Nerd Font"
+    property color barFg: Color.foreground
+    property string fontFamily: Style.font.family
 
     spacing: Style.space(4)