fix(web): service overview throughput uses the queried window - #1281

🟢 Confidence 9/10 · safe to merge
One-line divisor fix, the only windowDurationSeconds call in the file, pinned by a test that reads 100/3600 without it.
_{quality 100/100 · no findings · tests covered · risk low}

getServiceOverview now divides throughput by the resolved window it queried instead of the raw inputs, fixing a 24x-inflated rate on the default range. Contained and safe to merge.

• getServiceOverview divides by windowDurationSeconds(startTime, endTime), the resolved window
• New it.live test asserts 100 spans over the default 24h window

_{9896e14 · Updated on every push. Reply "won't fix" to dismiss a finding, or mention @maple-review-bot to ask about one.}