Repo delivery health across user projects

Delivery health of every repo linked to the caller's projects (project_repos), derived from GitHub App coverage and the deliveries the receiver saw — no repository hook is inspected. Coverage answers from the stored installation row when the owner's installation is on all repos; for an installation on selected repos (or one with no stored login yet) it asks GitHub which installation covers the repo (cached in process). Each repo carries a state: delivering (the GitHub App covers it and a delivery arrived inside the freshness window), quiet (covered, nothing lately — healthy), not_covered (no installation of the project's account reaches the repo; owner is who must install the App), or unknown (coverage could not be determined right now, never read as not covered). Delivery evidence (last_delivery_at, last_event, delivery_count) is returned only for covered repos. A repo linked by several projects reads as its best coverage. healthy counts delivering and quiet repos. Repos are keyed by canonical lowercase owner/repo.