fix: remove invalid single-instance capability + dead static tray icon

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src-tauri/capabilities/default.json

@@ -30,7 +30,6 @@
     "core:window:allow-set-fullscreen",
     "core:window:allow-is-fullscreen",
     "core:window:allow-create",
-    "core:webview:allow-create-webview-window",
-    "single-instance:default"
+    "core:webview:allow-create-webview-window"
   ]
 }

src-tauri/tauri.conf.json

@@ -29,12 +29,6 @@
     ],
     "security": {
       "csp": null
-    },
-    "trayIcon": {
-      "iconPath": "icons/icon.png",
-      "iconAsTemplate": false,
-      "title": "Psysonic",
-      "tooltip": "Psysonic"
     }
   },
   "bundle": {