feat: add VITE_MAINTENANCE_MODE env var for service screen

Set VITE_MAINTENANCE_MODE=true in .env to show an "Under Service"
screen and block all transactions. No hardware init, no Lightning
connection — just a static screen.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/machine/src/App.vue

@@ -33,6 +33,16 @@ onMounted(async () => {
     })
   }
 
+  // Check maintenance mode before initializing anything
+  const config = isElectron ? await window.electronAPI?.getConfig() : null
+  const maintenanceMode =
+    config?.maintenanceMode || import.meta.env.VITE_MAINTENANCE_MODE === 'true'
+
+  if (maintenanceMode) {
+    atmStore.initError = 'maintenance'
+    return
+  }
+
   try {
     if (isElectron) {
       await atmStore.initializeForProduction()
@@ -88,11 +98,20 @@ function toggleLiveServices() {
         <line x1="12" y1="9" x2="12" y2="13" />
         <line x1="12" y1="17" x2="12.01" y2="17" />
       </svg>
-      <h1 class="text-2xl lg:text-[3.5rem] font-bold">ATM Unavailable</h1>
+      <h1 class="text-2xl lg:text-[3.5rem] font-bold">
+        {{ atmStore.initError === 'maintenance' ? 'Under Service' : 'ATM Unavailable' }}
+      </h1>
       <p class="max-w-md text-center text-base lg:text-2xl text-muted-foreground">
-        This machine is temporarily out of service. Please try again later or use another machine.
+        {{
+          atmStore.initError === 'maintenance'
+            ? 'This machine is currently being serviced. We will be back shortly.'
+            : 'This machine is temporarily out of service. Please try again later or use another machine.'
+        }}
       </p>
-      <p v-if="atmStore.debugMode" class="max-w-lg text-center font-mono text-sm text-destructive">
+      <p
+        v-if="atmStore.debugMode && atmStore.initError !== 'maintenance'"
+        class="max-w-lg text-center font-mono text-sm text-destructive"
+      >
         {{ atmStore.initError }}
       </p>
     </div>

apps/machine/src/types/electron.d.ts

@@ -15,6 +15,7 @@ export interface RuntimeConfig {
   cassettes?: string
   allowMockFallback: boolean
   operatorPubkeys: string
+  maintenanceMode: boolean
 }
 
 export interface AtmSecrets {