Show traffic totals for the selected metrics range

[arjunkomath]

Summary

• show ingress and egress summaries as total request/response body bytes for the selected metrics range
• keep the traffic chart, tooltip, and legend expressed as throughput in B/s
• query whole-window counter increases across proxy instances with reset-safe PromQL
• avoid stale totals and range-label mismatches while SWR retains previous data
• degrade individual total-query failures to unavailable values without failing other metrics

Validation

• npx tsc --noEmit
• npx biome check --write components/service/details/service-details-overview.tsx lib/victoria-metrics.ts tests/victoria-metrics-service-metrics.test.ts
• npm test -- --run tests/victoria-metrics-service-metrics.test.ts (5 tests passed)
• git diff --check

Review

Smart Review approved the query approach and identified stale-data, range-label, and test-coverage gaps; those findings are addressed in this PR.

[github-actions]

React Doctor found no new issues. 🎉

_{Reviewed by React Doctor for commit 3bfcee3.}