[Parent] Track and resolve recurring agentic workflow execution failures (non-rate-limit)

Recurring `[aw]` workflow runs are failing or producing no safe outputs for reasons unrelated to AI-credits rate limits. This parent tracks those failures for diagnosis and resolution.

## Sub-issues

- #1544 — Bash Step Hygiene Auditor failed
- #1533 — Clippy Fixer failed
- #1523 — Bash Step Hygiene Auditor failed
- #1493 — Bash Step Hygiene Auditor failed
- #1485 — Test Gap Finder failed
- #1483 — Copilot Model List Updater reported incomplete result
- #1459 — Bash Step Hygiene Auditor failed
- #1435 — Test Reducer produced no safe outputs

## Goal

Identify root causes (broken tooling, flaky pipelines, infrastructure issues, prompt regressions) and resolve or close each failure report. Rate-limit failures are tracked separately in #1535.

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Start by reading the listed sub-issues (#1544, #1533, #1523, #1493, #1485, #1483, #1459, and #1435) and inspect their workflow execution details. Done means identifying the root cause of each non-rate-limit failure and resolving or closing each failure report.

Written by the indexing model from the issue text.