fix: merge plugin tools into builtin toolsets

toolsets.py

@@ -521,13 +521,18 @@ def get_toolset(name: str) -> Optional[Dict[str, Any]]:
         None: If toolset not found
     """
     toolset = TOOLSETS.get(name)
-    if toolset:
-        return toolset
 
     try:
         from tools.registry import registry
     except Exception:
-        return None
+        return toolset if toolset else None
+
+    if toolset:
+        merged_tools = sorted(
+            set(toolset.get("tools", []))
+            | set(registry.get_tool_names_for_toolset(name))
+        )
+        return {**toolset, "tools": merged_tools}
 
     registry_toolset = name
     description = f"Plugin toolset: {name}"