Track distributed agent decision limiter storage

[JOY]

Context

PR #10 adds in-memory per-player rate limiting and daily token budgeting for /v1/agent/decide. That is acceptable for the current single-gateway prototype, but it does not coordinate usage across multiple gateway instances.

Required Before Scaling

• Move agent decision request limits to Redis or another shared store.
• Move daily token budgets to a shared atomic counter keyed by trusted player identity.
• Preserve local disabled-limit behavior when config values are zero for development.
• Add tests for concurrent budget increments and retry-after behavior.

Notes

This is intentionally tracked outside PR #10 so the current prototype can enforce budget gates without introducing distributed infrastructure prematurely.