TEI request duration histogram

TEI main, router/src/lib.rs line ~661: metrics::histogram!("te_request_duration") .record(self.start_time.elapsed().as_secs_f64()). Buckets come from router/src/prometheus.rs: Matcher::Suffix("duration") catches this name and builds a 35-bound geometric ladder starting at 1e-5 and multiplying by 1.5 each step. The arithmetic detail that matters: the loop multiplies FIRST and then pushes, so the first emitted bound is 1.5e-5 and 1e-5 itself is NOT a bound. Effective range is roughly 1.5e-5 s to 1.5e-5 * 1.5^34 ~= 2.6e4 s. This is whole-request latency, not a phase breakdown. NOTE the Suffix matcher is a substring match, so te_request_duration, te_request_queue_duration, te_request_tokenization_duration and te_request_inference_duration ALL share this one ladder - they are not separately configured.