🔍 Problem Statement

As a client admin, charge-upon-renewal only charges one renewal phase ahead, so paid phases added behind an intermittent free phase go uncharged and revenue is deferred.

💡 User Story

As a client admin, I want to set how many renewal phases ahead charge-upon-renewal charges from the platform admin dashboard, so that paid phases sitting behind free or stacked phases are collected when they're added.

🎯 Definition of Done (DoD)

1. ✔ Given charge-upon-renewal is enabled and the look-ahead is set to N phases in the admin dashboard, when a subscription has N or fewer phases before a paid phase, then that paid phase is charged on the spot.

2. ✔ Given the admin dashboard setting, when an admin saves the look-ahead value, then it persists per site and defaults to 1 for existing accounts.

3. ✔ This change will impact UI and API, specifically the charge-upon-renewal settings screen in the admin dashboard and its backing configuration endpoint.

4. ✔ This solution will include the following limitations: applies only when charge-upon-renewal is enabled; does not retroactively charge phases on existing subscriptions; look-ahead is a per-site setting, not per-plan or per-subscription. [clarify: confirm per-site scope]