Apply dashboard filters to demo analytics

[thebuilder]

Summary

• make demo analytics filters affect breakdowns, events, flags, totals, and cross-dimension reports
• keep demo range, path, and growth scaling consistent while filters are active
• refresh the analytics documentation screenshots and add a filtered-dashboard example

Root cause

The demo overview totals and trend respected active filters, but breakdown, event, and flag reports returned fixed rows. This made filters appear broken and left the dashboard internally inconsistent.

Verification

• dotnet test --no-restore --filter FullyQualifiedName~MockVercelAnalyticsClientTests — 8 passed
• confirmed the screenshot set includes the overview, audience/events/flags, custom-event details, and filtered dashboard states
• left the unchanged settings screenshot untouched

Filtered dashboard