Every shop page load was triggering ~18 DB queries for data that rarely
changes (theme settings, nav items, categories, shipping countries, logo,
header image). On a shared-cpu-1x Fly machine with SQLite this was the
primary performance bottleneck.
- Add SettingsCache GenServer+ETS for all non-encrypted settings
- Cache list_categories() with single-query N+1 fix (correlated subquery)
- Cache list_available_countries_with_names() in shipping
- Cache Media.get_logo() and Media.get_header()
- Remove duplicate LoadTheme plug from :shop and :admin pipelines
- Invalidate caches on writes (put_setting, product sync, media upload)
- Clear caches between tests via DataCase/ConnCase setup
Per-page queries reduced from ~18 to ~2.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
