Add warning when BTC and sats exceed the maximum

Sources/SatsPrice/ContentView.swift

@@ -88,6 +88,10 @@ public struct ContentView: View {
 #endif
             } header: {
                 Text("Sats")
+            } footer: {
+                if satsViewModel.exceedsMaximum {
+                    Text("2100000000000000 sats is the maximum.")
+                }
             }
 
             Section {
@@ -97,6 +101,10 @@ public struct ContentView: View {
 #endif
             } header: {
                 Text("BTC")
+            } footer: {
+                if satsViewModel.exceedsMaximum {
+                    Text("21000000 BTC is the maximum.")
+                }
             }
 
             Section {

Sources/SatsPrice/Resources/Localizable.xcstrings

@@ -16,6 +16,12 @@
     },
     "1 BTC to %@" : {
 
+    },
+    "21000000 BTC is the maximum." : {
+
+    },
+    "2100000000000000 sats is the maximum." : {
+
     },
     "BTC" : {
 

Sources/SatsPrice/SatsViewModel.swift

@@ -190,6 +190,13 @@ class SatsViewModel: ObservableObject {
         }
 #endif
     }
+
+    var exceedsMaximum: Bool {
+        if let btc, btc > Decimal(21000000) {
+            return true
+        }
+        return false
+    }
 }
 
 extension Decimal {