Add admin controls to rewards portal

[ethgr0wth]

Summary

• add role-aware authentication with admin-only endpoints for pool management, node moderation, and payout exports
• persist pool balances in Redis, respect node status during monitoring and rewards, and expose CSV-friendly payout snapshots
• surface an admin control center in the frontend with balance adjustments, daily payout updates, node rejection/reinstatement, and export tooling

Testing

• PYENV_VERSION=3.11.12 pytest tests/test_rewards.py

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https://chatgpt.com/codex/tasks/task_e_68f195a2ef54833387184a412e589db3