v4.16.4 — perception scale, brand-name extraction, schema @graph

What's Changed

• fix(citability): count Instagram, TikTok and Threads as platforms by @auriti in #521
• chore(ci): bump checkout and setup-python to v7 across every surface by @auriti in #522
• fix(ops): sync deploy-reliability fixes from sync/fixes-to-site by @auriti in #523
• feat(analytics): GA4 begin_checkout + cross-domain session stitching by @auriti in #524

Full Changelog: v4.16.3...v4.16.4