add minimum fee rates source of static 1 sat/vb for all block targets

src/main/java/com/sparrowwallet/sparrow/net/FeeRatesSource.java

@@ -35,6 +35,17 @@ public enum FeeRatesSource {
             String url = "https://bitcoinfees.earn.com/api/v1/fees/recommended";
             return getThreeTierFeeRates(defaultblockTargetFeeRates, url);
         }
+    },
+    MINIMUM("Minimum (1 sat/vB)") {
+        @Override
+        public Map<Integer, Double> getBlockTargetFeeRates(Map<Integer, Double> defaultblockTargetFeeRates) {
+            Map<Integer, Double> blockTargetFeeRates = new LinkedHashMap<>();
+            for(Integer blockTarget : defaultblockTargetFeeRates.keySet()) {
+                blockTargetFeeRates.put(blockTarget, 1.0);
+            }
+
+            return blockTargetFeeRates;
+        }
     };
 
     private static final Logger log = LoggerFactory.getLogger(FeeRatesSource.class);

src/main/resources/com/sparrowwallet/sparrow/preferences/general.fxml

@@ -49,6 +49,7 @@
                             <FeeRatesSource fx:constant="ELECTRUM_SERVER" />
                             <FeeRatesSource fx:constant="MEMPOOL_SPACE" />
                             <FeeRatesSource fx:constant="BITCOINFEES_EARN_COM" />
+                            <FeeRatesSource fx:constant="MINIMUM" />
                         </FXCollections>
                     </items>
                 </ComboBox>

src/main/resources/com/sparrowwallet/sparrow/soroban/initiator.fxml

@@ -42,7 +42,7 @@
                     <center>
                         <VBox spacing="15">
                             <HBox styleClass="field-box">
-                                <Label text="Payment code or PayNym:" styleClass="field-label" />
+                                <Label text="PayNym or Payment code:" styleClass="field-label" />
                                 <HBox>
                                     <StackPane>
                                         <ComboBox fx:id="payNymFollowers" />