When user presses Esc during tool argument streaming, the assistant
message ends with stopReason="aborted" but tool execution never starts.
Now we check for aborted/error stopReasons in message_end and update
all pending tool execution components to show red error state with
"Operation aborted" message.
This fixes the issue where tool components stayed stuck in blue/pending
state after aborting during JSON streaming.
2fdd304fbf