fix: extend admitted business turn window

[veil-chow-fyaic]

Observed blocker

Fresh real attempt 5 on main@cbdccfb validated the exact phase-tool contract and autonomously completed kickoff publication, reviewer accept/admit, two-tool review publication, irrelevant skip, and same-A acceptance. The same-A admitted fix turn then reached threadmesh_codex_live_context_reconciliation_ambiguous inside the existing 180-second product-operation window. No retry, verifier activation, or dependent effect occurred; normal cleanup passed 5/5.

Bounded correction

Extend only protected admitted business turns from 180 to 300 seconds. Bootstrap, ordinary kickoff, receiver decision, cleanup, and reconciliation semantics are unchanged. Ambiguous outcomes remain reconcile-only and cannot be resent.

Evidence

• 44 focused event-pump/product-turn tests pass;
• docs lint: 106 files, 0 findings;
• canonical attempt audit and status now retain attempt 5 as the first real autonomous partial chain.

Boundary

This is not heartbeat, OS-kill recovery, a new supervisor, or a claim that the full chain passed.