fix(machine): hide theme toggle in dev mode when debug panel available

The debug panel already has full theme/color mode controls, so the
floating light/dark toggle is redundant in dev. Keep it for production.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/machine/src/App.vue

@@ -2,9 +2,9 @@
 import { onMounted, onUnmounted, ref, computed } from 'vue'
 import { useAtmStore } from '@/stores/atm'
 import { useTheme } from '@/composables/useTheme'
-import { Sun, Moon } from 'lucide-vue-next'
 import { Badge } from '@/components/ui/badge'
 import { Button } from '@/components/ui/button'
+import { Sun, Moon } from 'lucide-vue-next'
 
 const atmStore = useAtmStore()
 const { current: currentTheme, themes, colorMode } = useTheme()
@@ -130,8 +130,9 @@ function toggleLiveServices() {
         </Badge>
       </div>
 
-      <!-- Light/dark toggle (always visible) -->
+      <!-- Light/dark toggle (production only — debug panel has this in dev) -->
       <Button
+        v-if="!atmStore.allowMockFallback"
         variant="outline"
         size="kiosk"
         class="fixed bottom-6 right-6 z-50 gap-3"