feat: redesign Checklist Oven dashboard

[alowpoly]

Summary

• align the Checklist detail view with the shared Oven dashboard structure
• add KPI, progress ledger, compact burn chart, and expandable completion-event cards
• show the selected Checklist title and update time in the global header
• keep Checklist styles scoped and add focused rendering/chart coverage

Verification

• npm run build:dashboard
• node --test dashboard/src/components/ChecklistDashboard/ChecklistDashboard.test.mjs dashboard/src/lib/checklist-progress-chart.test.mjs
• npm run verify
• npm run verify:package