Use effective fee rates in mempool block visualizations & tooltips

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

@@ -71,6 +71,7 @@ export interface TransactionStripped {
   fee: number;
   vsize: number;
   value: number;
+  rate?: number; // effective fee rate
   status?: 'found' | 'missing' | 'fresh' | 'added' | 'censored' | 'selected';
   context?: 'projected' | 'actual';
 }