Add indicator for being in debug mode

AppDrawer.tsx

@@ -1,6 +1,6 @@
 import { createDrawerNavigator } from "@react-navigation/drawer";
 import { StackScreenProps } from "@react-navigation/stack";
-import { IconButton, useTheme } from "react-native-paper";
+import { IconButton, useTheme, Banner } from "react-native-paper";
 import { DrawerParams } from "./drawer-params";
 import ExerciseList from "./ExerciseList";
 import GraphsList from "./GraphsList";
@@ -10,6 +10,7 @@ import SetList from "./SetList";
 import SettingsPage from "./SettingsPage";
 import TimerPage from "./TimerPage";
 import WeightList from "./WeightList";
+import { StyleSheet, Text, View } from "react-native";
 
 const Drawer = createDrawerNavigator<DrawerParams>();
 
@@ -23,6 +24,12 @@ export default function AppDrawer({
   const { dark } = useTheme();
 
   return (
+    <>
+      {__DEV__ && (
+        <View style={styles.debugBanner}>
+          <Text style={styles.debugText}>DEBUG</Text>
+        </View>
+      )}
       <Drawer.Navigator
         screenOptions={{
           headerTintColor: dark ? "white" : "black",
@@ -78,5 +85,25 @@ export default function AppDrawer({
           options={{ drawerIcon: () => <IconButton icon="cog-outline" /> }}
         />
       </Drawer.Navigator>
+    </>
   );
 }
+
+const styles = StyleSheet.create({
+  container: {
+    flex: 1,
+  },
+  debugBanner: {
+    position: 'absolute',
+    top: 0,
+    right: 0,
+    transform: [{ rotate: '45deg' }],
+    backgroundColor: 'red',
+    zIndex: 1000,
+  },
+  debugText: {
+    color: 'white',
+    padding: 5,
+    fontSize: 10,
+  },
+});