fix(gui): Skip empty strings in selectable to prevent ImGui ID assertion

Empty strings in bias_profiles.keys() and personas.keys() caused
imgui.selectable() to fail with 'Cannot have an empty ID at root of
window' assertion error. Added guards to skip empty names.

opencode.json

@@ -71,5 +71,6 @@
       "logs/**",
       "*.log"
     ]
-  }
+  },
+  "plugin": ["superpowers@git+https://github.com/obra/superpowers.git"]
 }