When the LLM outputs text containing tool call patterns (e.g., reading
log files, showing examples, or discussing tool calls), the parser's
has_unexecuted_tool_call() would detect these as real tool calls and
trigger auto-continue, leading to repeated empty responses.
The fix: mark the parser buffer as consumed when content is displayed.
This prevents tool-call-like patterns in displayed text from triggering
false positives later. The fix is safe because:
1. Only runs when no tool was detected (inside 'if !tool_executed')
2. Legitimate tool calls are detected first by process_chunk()
3. Matches existing pattern of calling mark_tool_calls_consumed()
after tool execution