[chriswessels]

Indexer-query histograms receive milliseconds in both query paths, and the targeted client-query path also records milliseconds, while ordinary client queries record seconds. A 250 ms observation is therefore recorded as 250 instead of 0.25 in histograms with default seconds buckets.

Route duration observations through Duration-accepting methods that convert to seconds, and document the unit in metric help text. Tests verify sample count, sum, and every finite default bucket for a 250 ms observation. Metric names remain unchanged; historical mixed-unit observations must be analyzed separately across the deployment boundary.

Validation (on this independent branch):

• cargo +nightly-2026-06-11 fmt --all -- --check
• cargo +1.95.0 clippy --all-targets --all-features -- -Dwarnings --force-warn deprecated --force-warn dead-code
• cargo +1.95.0 test