Plugin/custom tool renderers can return a component whose render() throws
(e.g. a plugin styling its header off an object without a bold method,
producing TypeError: th.bold is not a function). ToolExecutionComponent only
caught the renderCall/renderResult factory, not the child component's later
render() pass, so the exception escaped and crashed the transcript.
Wrap every renderer-returned call/result component in SafeToolRendererComponent,
which catches render() errors and falls back to the tool label (call) or raw
result text (result), logging once per component.
Fixes#4978
can1357