P2E: add reward observability and runbooks

[ilyar]

Source PRD: tasks/prd-full-play-to-earn.md
Parent epic: #86
PRD section: US-013

Description

Reward failures need dashboard metrics, alerts, correlation IDs, and recovery runbooks.

Acceptance Criteria

• Dashboard shows active campaigns, pool remaining, reserved rewards, paid rewards, failed payouts, held claims, abuse holds, and provider errors.
• Alerts fire on payout webhook failure, pool exhaustion, duplicate payout attempt, provider outage, abnormal claim volume, and high rejection rate.
• Reward events have correlation IDs across match settlement, reward allocation, claim, payout, and admin audit.
• Runbooks document reward pool recovery, provider retry, accidental over-allocation, and payout dispute handling.

Constraints

• Keep current paid PvP settlement as entry fee, not player-funded prize pool.
• Do not make Season Points redeemable or refundable.
• Keep payout/compliance/provider secrets backend-only.
• Treat this as deferred future-phase work until mechanics/self-host production readiness is stable.

Notes

This should extend operations visibility without leaking provider secrets, KYC details, or internal abuse thresholds.