fix: add enabled:true to PayOpsTask.grader Python property for platform compatibility

Fix: add grader property to PayOpsTask, include grader in grade_episode per_task_rewards, add per-task grader definitions to openenv.yaml

Fix stale docstring: 20→30 tasks with per-tier counts

Iteration_4: expand task bank 20→30, add variants for all tasks, fix baseline policy for chain-gated CRIT tasks

feat: seed-variant pool + chain gate enforcement

feat: enforce investigation discipline + fix easy-task grading + add investigation_hints

feat: Iteration_2 — trajectory reward shaping, episode jitter, flag identification

Initial Commit