#804 Stage 5 epic: HITL v2 - edit-args, timeout, escalation (#agentic)

Replay-safe arg editing: approval decision via durable wait_for_event payload -> merge args={**args,**edited_args} before dispatch (pure fn of durable data). approve API/MCP accepts edited_args, validate keys subset of recorded approval_data.arguments (no smuggling). Merge in agent.py approval dispatch + synthetic 'args modified by reviewer' note. Per-spec approval expiry + on_timeout reject|escalate (escalate=email/telegram notify, app layer). Dashboard approvals JSON arg editor. Formalize rejection shape {error: rejected_by_human, feedback}. Gates: harness + hitl_edit_args + hitl_timeout_reject; keep no-edit path byte-identical.