v5.1.0

• test: remove lease heartbeat timing race
• ci: resolve a3s-search 1.4.1 standalone
• chore: release v5.1.0
• test: validate AgentLoop through Codex login
• feat: integrate a3s-search 1.4.1
• feat: expose Flow decision dispatch health
• feat: renew Flow decision leases during dispatch
• test: benchmark agent convergence end to end
• feat: persist Flow decision claims across nodes
• feat: prevent distributed graph lost updates
• perf: make reactive graph projection scale
• fix: preserve convergence limits across resume
• feat: stop agent loops that make no progress
• feat: bridge Flow history into reactive graph
• docs: surface reactive state graph architecture