Handle status broken pipe output

[yvette-carlisle]

Summary:

• handle downstream-closed stdout pipes when printing decodex status output
• cover write and flush BrokenPipe cases in operator status tests
• document status broken-pipe behavior in runtime/operator references

Validation:

• cargo make fmt
• cargo make lint-fix
• cargo test -p decodex operator_status_output_accepts_closed_downstream_pipe
• cargo make test (1182 passed, 1 skipped)