Update .blockers.env PR #11790 row to reflect 06-15 cross-agent handoff

From 2026-06-16 self-reflection. Atomic single-file edit. Workspace-internal. The PR #11790 row in ~/agents/slava-agent/.blockers.env currently reads: ``` PR_NUMBER=11790 LAST_DM_AT=2026-06-13T05:39:00Z NEXT_RECHECK=2026-06-20T05:39:00Z NOTES=Asymmetric-ownership surface-to-Slava; awaiting his pick (a/b/c). ``` Update to: ``` PR_NUMBER=11790 LAST_DM_AT=2026-06-13T05:39:00Z LAST_OBSERVED_AT=2026-06-15T16:25:36Z NEXT_RECHECK=2026-06-23T05:39:00Z NOTES=Cross-agent handoff observed 2026-06-15T16:25Z (texture-coding-agent c201fb07 on Richie V-notch repro; PR currently CONFLICTING due to drift). Slava implicitly chose cross-agent path over a/b/c three-option ask from 2026-06-13. Do NOT re-DM Slava about a/b/c. Mute extended 14d from cross-agent push. If PR closes/merges, resolve the row. If a NEW Cato fix-push is requested by Slava, treat as fresh asymmetric-ownership situation (reset escalation counter). ``` ATOMIC STEPS: 1. Read current .blockers.env. 2. Locate the PR_NUMBER=11790 block. 3. Apply the replacement. 4. Verify with grep. 5. PATCH this task to completed via bin/fleet-task-patch.sh with the file line count and the updated block.