feat: update app name and adaptive icon background color for improved branding

MobileApp/app.json

@@ -1,6 +1,6 @@
 {
   "expo": {
-    "name": "OneUptime",
+    "name": "OneUptime On-Call",
     "slug": "oneuptime-on-call",
     "version": "1.0.0",
     "orientation": "portrait",
@@ -26,7 +26,7 @@
     "android": {
       "adaptiveIcon": {
         "foregroundImage": "./assets/adaptive-icon.png",
-        "backgroundColor": "#0D1117"
+        "backgroundColor": "#000000"
       },
       "edgeToEdgeEnabled": false,
       "package": "com.oneuptime.oncall",