feat(analytics): add admin analytics for hosted sites

[vigneshrajsb]

Description

• Adds GET /api/v2/admin/analytics/sites (administrator only) for a new Sites view in Analytics.
• Reports publishing activity (new sites, content updates, publishers) over the shared calendar window with previous-period comparison, plus owner types and visibility per bucket.
• Reports current state at request time: live sites, storage used (live plus restorable), current site states, and the top publishers and largest live sites.
• Reports endings, TTL extensions, and site lifetimes in the window, using the existing site audit trail for restores and extensions.
• Filters: ownerKind, visibility, and owner (an opaque publisher key returned in publisherOptions).
• No migrations or new tracking. Five read-only queries run in one repeatable-read transaction with the shared timeout. JIT compilation is turned off for that transaction.

Test plan

• Service, route, and OpenAPI contract tests, including 401/403/400 paths, no-store, NUL rejection, and bound filter values. Full Jest suite and lint pass.
• Checked results against a hand-computed fixture on a local PostgreSQL with the full migrated schema.
• EXPLAIN ANALYZE on a synthetic dataset with 50k sites, 200k versions, and 500k audit events: about 0.9 s for all queries combined, with a 180-day scan.
• In a preview environment, open Analytics > Sites as an administrator and compare a few numbers with the Sites list.