fix: support unprefixed tools in code_execution extension

The load_callback_configs function was failing when encountering
unprefixed tools (like summon's load/delegate) because it expected
all tool names to contain '__'. Now uses get_tool_owner() to get
the namespace for unprefixed tools, making them available in code
execution mode as Summon.load() and Summon.delegate().

crates/goose/src/agents/code_execution_extension.rs

@@ -1,4 +1,5 @@
 use crate::agents::extension::PlatformExtensionContext;
+use crate::agents::extension_manager::get_tool_owner;
 use crate::agents::mcp_client::{Error, McpClientTrait};
 use anyhow::Result;
 use async_trait::async_trait;
@@ -111,10 +112,16 @@ impl CodeExecutionClient {
         let mut cfgs = vec![];
         for tool in tools {
             let full_name = tool.name.to_string();
-            let (server_name, tool_name) = full_name.split_once("__")?;
+            let (namespace, name) = if let Some((server, tool_name)) = full_name.split_once("__") {
+                (server.to_string(), tool_name.to_string())
+            } else if let Some(owner) = get_tool_owner(&tool) {
+                (owner, full_name)
+            } else {
+                continue;
+            };
             cfgs.push(CallbackConfig {
-                name: tool_name.into(),
-                namespace: server_name.into(),
+                name,
+                namespace,
                 description: tool.description.as_ref().map(|d| d.to_string()),
                 input_schema: Some(json!(tool.input_schema)),
                 output_schema: tool.output_schema.as_ref().map(|s| json!(s)),