fix(runtime): add 30s timeout to tool execution in AgentLoop

Tool execution (ShellExec, WebFetch, etc.) had no timeout, causing the
entire streaming response to hang indefinitely when a tool fails or stalls.
Now wraps execute_tool calls in tokio::time::timeout(30s) with a graceful
error message on timeout.

crates/zclaw-runtime/src/loop_runner.rs

@@ -429,10 +429,17 @@ impl AgentLoop {
                             continue;
                         }
                         middleware::ToolCallDecision::ReplaceInput(new_input) => {
-                            // Execute with replaced input
-                            let tool_result = match self.execute_tool(&name, new_input, &tool_context).await {
-                                Ok(result) => result,
-                                Err(e) => serde_json::json!({ "error": e.to_string() }),
+                            // Execute with replaced input (with timeout)
+                            let tool_result = match tokio::time::timeout(
+                                std::time::Duration::from_secs(30),
+                                self.execute_tool(&name, new_input, &tool_context),
+                            ).await {
+                                Ok(Ok(result)) => result,
+                                Ok(Err(e)) => serde_json::json!({ "error": e.to_string() }),
+                                Err(_) => {
+                                    tracing::warn!("[AgentLoop] Tool '{}' (replaced input) timed out after 30s", name);
+                                    serde_json::json!({ "error": format!("工具 '{}' 执行超时（30秒），请重试", name) })
+                                }
                             };
                             messages.push(Message::tool_result(id, zclaw_types::ToolId::new(&name), tool_result, false));
                             continue;
@@ -471,9 +478,16 @@ impl AgentLoop {
                     }
                 }
 
-                let tool_result = match self.execute_tool(&name, input, &tool_context).await {
-                    Ok(result) => result,
-                    Err(e) => serde_json::json!({ "error": e.to_string() }),
+                let tool_result = match tokio::time::timeout(
+                    std::time::Duration::from_secs(30),
+                    self.execute_tool(&name, input, &tool_context),
+                ).await {
+                    Ok(Ok(result)) => result,
+                    Ok(Err(e)) => serde_json::json!({ "error": e.to_string() }),
+                    Err(_) => {
+                        tracing::warn!("[AgentLoop] Tool '{}' timed out after 30s", name);
+                        serde_json::json!({ "error": format!("工具 '{}' 执行超时（30秒），请重试", name) })
+                    }
                 };
 
                 // Check if this is a clarification response — terminate loop immediately