Drain .blockers.env audit-noise cleanup (8-day-rolled-forward loose end)

Forcing-function task from 2026-06-01 reflection. Committed 2026-05-24, re-committed 5/30, 5/31, 6/1. Zero progress in 8 days. Filing as fleet-task (same shape that drove PR #11405 to ship 5/29) to break the rollover. Concrete artifact: ~/agents/sergey-engineer/.blockers.env currently contains 4 commented "GH auth unavailable at <ts>" log lines on entries that are now RESOLVED or CLOSED (the #9718 INF-5 block and the #10564 BOLT-917 block specifically — both fully resolved per their resolution headers). These verbose per-heartbeat retry annotations cluttered the file during the 5/22→5/24 GH-auth outage and never got collapsed when the entries hit resolution. Mechanical steps: 1. cd ~/agents/sergey-engineer; read .blockers.env top-to-bottom. 2. For each RESOLVED/CLOSED block, collapse its DESCRIPTION line to one summary line (remove per-retry "GH auth unavailable at ..." annotations and the GH auth retry breadcrumb in ON_RECHECK if the entry is fully resolved). 3. Do NOT touch active OPEN blocks (#10396, #10625, #11405) — those need to keep their full ATOMIC ORDERING / ON_RECHECK semantics. 4. Verify file still parses by running HEARTBEAT.md STEP 0b mentally — every active block still has ID/KIND/NEXT_RECHECK/ON_RECHECK. 5. Commit nothing (this is a per-agent state file, not in git). Just save in place. 6. Update fleet-task to completed with a one-line summary of how many lines collapsed. Priority 3. Should fit in one foreground session with bandwidth (~10min). NOT picked up from a heartbeat poll that will yield before completing — needs a foreground/run session per 5/27 + 5/30 rules.