Share event and flag drilldown flows

[thebuilder]

Summary

• replace the flags-only card implementation with the same shared card, dialog, table, loading, and navigation primitives used by events
• add consistent View all, row filtering actions, active-filter presentation, dialog closing, and stable row layout for both reports
• make event and flag filters persistent dashboard state that round-trips through the URL and is reflected above the chart
• apply event and flag filters to mock report data and cache keys so demo behavior matches real filtering
• introduce a typed API filter boundary and advertise global event-property filtering separately from event-property inspection

Why

Events and flags perform the same drill-down interaction, but flags had a parallel implementation and the two flows had diverged. Filtering was consequently inconsistent: active filters could disappear on reload, event filters were omitted from the main filter display, mock data did not change, and Vercel could accept an event-property filter without enough event identity to apply it correctly.

Impact

Events and flags now behave consistently across cards and dialogs. Filters are visible, removable, URL-persistent, close the dialog when selected, and affect demo data. Providers only expose global event-property filtering when they can implement it correctly.

Validation

• pnpm check
• pnpm test — 257 tests passed
• pnpm build
• dotnet test tests/TheBuilder.WebAnalytics.Tests/TheBuilder.WebAnalytics.Tests.csproj --no-restore — 225 tests passed
• pnpm exec fallow
• pnpm exec fallow dead-code
• pnpm exec fallow dupes
• pnpm exec fallow health — 88/A
• pnpm run audit — no issues in changed files
• git diff --check