Add extended promotional component filter

[chriszlr]

Summary

• expose is_extended_promotional on /api/search and /components/list responses
• add is_extended_promotional=true filtering derived from preferred = 1 and basic = 0
• wire the same filter/field through the D1 proxy search and components list paths, including the components UI checkbox
• add regression coverage for the core routes and proxy render path

Tests

• bun run format:check
• bunx tsc --noEmit --pretty false
• cd cf-proxy && bunx tsc --noEmit --pretty false
• cd cf-proxy && bun test test/render.test.ts
• minimal SQLite smoke test for /api/search?is_extended_promotional=true and /components/list?json=true&is_extended_promotional=true

/claim #92