Implements an actix-web middleware that optionally validates a Bearer token against a server-configured TURBO_TOKEN. When no token is configured, all requests pass through. Otherwise, it parses the Authorization header, verifies the Bearer scheme case-insensitively, and compares the token using constant-time comparison via the `subtle` crate to prevent timing-based enumeration. Errors are returned as JSON with an appropriate error message and the WWW-Authenticate header. This module is self-contained (depends only on actix-web, serde, secrecy, and subtle) and could be extracted into any actix-web project that needs a similar optional authentication guard.

Configures the entire telemetry stack: Bunyan-format JSON logging (to stdout and optionally a rolling file), log-to-trace bridging via tracing-log, and OpenTelemetry trace/metric export over OTLP (gRPC or HTTP). The module respects the OTEL_SDK_DISABLED environment variable to entirely suppress the OTLP layers. It also sets up three system metric gauges (CPU utilization, memory usage, virtual memory) using sysinfo and OpenTelemetry observable gauges, all annotated with the service name and version. The subscriber is assembled using tracing-subscriber's layered architecture, making it easy to add or remove sinks. This code is a reusable pattern for any Rust application that wants a production-ready telemetry setup with optional OTLP export, file logging, and process-level metrics.