fix sandbox metrics chart

[luke-lombardi]

Summary by cubic

Fixes the sandbox metrics chart by scoping resource metrics to the selected app and correctly populating active sandbox timing.

• Bug Fixes
  • Add app-scoped filtering to metrics timeseries: read app_id from the API, pass it in EventQuery, and filter S2 records by header or payload so charts only include the selected app.
  • Include AppID in EventContainerMetricsSchema and propagate through repositories and CloudEvents extensions to enable accurate matching.
  • Correct active sandbox timing: stop defaulting TimeToInteractiveMs/InteractiveAtMs to started time, allow history summary to override fields, and adjust summary-needed logic. Tests added for app scoping and timing enrichment.

^{Written for commit bef2705. Summary will update on new commits.}