fix: show correct history chart data for registry/task-runner averages

[vltbaudbot]

Summary

The Performance Over Time history chart was showing package manager average data on the registry and task-runner average pages. While PR #134 fixed the bar charts by passing isRegistryRoute/isTaskExecutionRoute props, the underlying history data was still using the PM-only synthetic average.

Problem

When visiting /registries/average or /task-runners/average, the history chart looked up historyData.variations["average"] which was always computed from package management variations (clean, cache, lockfile, etc.). This meant the line graph showed PM average performance instead of registry/task-runner average performance.

Changes

app/src/hooks/use-history-data.ts

• Extracted the synthetic average computation into a reusable computeSyntheticAverage helper
• Now computes three synthetic average keys:
  • "average" — from PM variations (clean, node_modules, cache, etc.)
  • "registryAverage" — from registry variations (registry-clean, registry-lockfile)
  • "taskRunnerAverage" — from task-runner variations (build, build-cache, run)

app/src/components/history-chart.tsx

• When on the average variation with isRegistryRoute, looks up "registryAverage" instead of "average"
• When on the average variation with isTaskExecutionRoute, looks up "taskRunnerAverage" instead of "average"
• Package manager average page continues to use "average" as before

Testing

The fix ensures each average page's history chart matches its bar chart data source:

• PM average page → history from PM variations ✅ (unchanged)
• Registry average page → history from registry variations ✅ (fixed)
• Task-runner average page → history from task-runner variations ✅ (fixed)

Co-authored-by: Darcy Clarke darcy@darcyclarke.me