Health Check

Health check endpoint for monitoring and load balancers.

Returns status: "ok" only when an agent is registered and /agent/* will accept requests. Returns status: "degraded" with agent_ready: false when no agent is configured — e.g. standalone admin-only mode after an assemble_engine_config error, or the pre-onboarding wizard state. When app.state.boot_error is set by the standalone's assembly failure handler, it is surfaced as reason so operators can diagnose without grepping logs.