chore: vendor sglang v0.5.10 snapshot

third_party/sglang/sgl-model-gateway/src/observability/mod.rs

@@ -0,0 +1,8 @@
+//! Observability utilities for logging, metrics, and tracing.
+
+pub mod events;
+pub mod gauge_histogram;
+pub mod inflight_tracker;
+pub mod logging;
+pub mod metrics;
+pub mod otel_trace;