[mining] use .slug to load pool logo

frontend/src/app/interfaces/node-api.interface.ts

@@ -110,6 +110,7 @@ export interface PoolInfo {
   regexes: string; // JSON array
   addresses: string; // JSON array
   emptyBlocks: number;
+  slug: string;
 }
 export interface PoolStat {
   pool: PoolInfo;