Customer Activity Metrics + Acquisition Funnel

🔍 Problem Statement As an analytics user, I open the Customers Activity page to only a raw event feed, forcing CSV exports and external joins to understand conversion.

💡 User Story As an analytics user, I want an overview band with summary metrics and an acquisition funnel on the Customers Activity page, so that I can read conversion at a glance without exporting.

As a marketing user, I want each card and funnel step to filter the event list on click, so that I can drill into the customers behind any number.

🎯 Definition of Done (DoD)

✔ Given the Customers Activity page loads, then an overview band shows four cards — Paywall Views, Overall Conversion, Checkout Abandonment, Renewal Rate — scoped to the active date range. [clarify: Renewal Rate denominator — events-only (Renewed ÷ Renewed + Renewal Failed) vs billing "due" count]

✔ Given the page's existing date filter, when the user changes it, then all cards, the funnel, and the page list recalculate to that range, with no separate date control added.

✔ Given the overview band, when rendered, then an Acquisition Funnel shows steps Paywall Displayed → Plan Viewed → Checkout Started → Registered → Subscription Created, each with a count and step-to-step conversion rate.

✔ Given the overview, when rendered, then a Top Converting Pages list ranks page paths by attributed Subscription Created count, showing the top 10 with conversions per path.

✔ Given any card, funnel step, or page row, when the user clicks it, then the activity list filters to the matching events.

1. export should work fine with the filters