/// Token-based authentication for admin endpoints.
/// SQLite persistence for request logs and config overrides.
/// Background health-checker: probes backends every 30 seconds.
/// Virtual API key generation, hashing, and rate limit state.
/// Admin HTTP router: config management, request log queries, metrics.
/// Per-key spend queries for cost tracking.
/// Shared mutable state between proxy handlers and admin server.
/// WebSocket handler for live admin event streaming.
pub