Send mempool effective fee rate changes to frontend & apply

frontend/src/app/interfaces/websocket.interface.ts

@@ -54,6 +54,7 @@ export interface MempoolBlockWithTransactions extends MempoolBlock {
 export interface MempoolBlockDelta {
   added: TransactionStripped[],
   removed: string[],
+  changed?: { txid: string, rate: number | undefined }[];
 }
 
 export interface MempoolInfo {