When the tool loop guardrail fires (max_tool_failures, etc.), the
turn exits with guardrail_halt but no final assistant message was
emitted to the client. The SSE stream closed silently —
indistinguishable from a crash.
The stream_delta_callback(None) before tool execution is a display
flush, not a hard close. After generating the halt response, emit
it through both _safe_print (CLI) and stream_delta_callback (SSE)
so clients see the explanation.
Fixes#30770
