fix(icons): remove remaining electrs icon references, use electrumx.png

GoalDetail.vue, EasyHome.vue, and the backend's docker_packages.rs
metadata still pointed electrs-family app ids at the old electrs
icon (svg). Point them at electrumx.png like every other reference,
and delete the now-unused electrs.svg asset.

core/archipelago/src/container/docker_packages.rs

@@ -396,7 +396,7 @@ fn get_app_metadata(app_id: &str) -> AppMetadata {
         "electrumx" | "mempool-electrs" | "electrs" => AppMetadata {
             title: "ElectrumX".to_string(),
             description: "ElectrumX server — full Electrum protocol indexer for Bitcoin. Powers Mempool and Electrum wallets.".to_string(),
-            icon: "/assets/img/app-icons/electrs.svg".to_string(),
+            icon: "/assets/img/app-icons/electrumx.png".to_string(),
             repo: "https://github.com/spesmilo/electrumx".to_string(),
             tier: "",
         },