Redis single core saturated

Every service that touches the shared Redis suddenly sees latency spike together at 11:20, sessions, rate-limiting, and feature flags all slow at once. Redis dashboards: the single Redis primary's CPU is pinned at 100% on one core (the box has spare cores), instantaneous_ops_per_sec is flat (not rising) while the slowlog fills up, and clients pile up in the connected-clients count. A new analytics feature deployed at 11:15 runs periodic KEYS pattern:* and large SMEMBERS calls against the same instance. Triage and mitigate.