Every published price tier as CSV

One row per provider × product × tier, in ladder order; products without a published ladder have no rows. Columns: slug, name, listing_status, type, pricing_model, price_unit, tier, kind, quantity, unit_price_usd, total_usd, effective_unit_price_usd, billing_period, note, price_from_usd, entry_price_usd, pricing_url, checked_at, page, once, ip_version, shared. effective_unit_price_usd is unit_price_usd for volume tiers and graduated bands and total_usd / quantity for plans, per the tier's own billing period. once is true for trial/one-time offers (never quoted); ip_version (ipv4, ipv6) and shared (true, false) are empty when the ladder does not say. Supports ETag / If-None-Match and database Last-Modified / If-Modified-Since.