Review/improve odk-central-frontend cache headers

[alxndrsn]

Related:

• Cloudflare caches Entity Lists for longer than expected #662
• Review/improve Enketo cache headers #949

path	current Cache-Control	current Vary	current Pragma	recommended strategy
/	no-cache	undefined	no-cache	revalidate
/client-config.json	no-cache	undefined	no-cache	revalidate
/css/app.7f75100b.css	no-cache	undefined	no-cache	immutable
/css/component-feedback-button.9b267cf5.css	no-cache	undefined	no-cache	immutable
/css/component-home-config-section.86dc3b10.css	no-cache	undefined	no-cache	immutable
/css/component-home.7fd2ac91.css	no-cache	undefined	no-cache	immutable
/css/component-hover-cards.f8d67159.css	no-cache	undefined	no-cache	immutable
/css/component-outdated-version.1669dac3.css	no-cache	undefined	no-cache	immutable
/favicon.ico	no-cache	undefined	no-cache	revalidate
/fonts/icomoon.ttf?ohpk4j	no-cache	undefined	no-cache	immutable
/js/1272.6c131f2a.js	no-cache	undefined	no-cache	immutable
/js/247.f8ae2d8d.js	no-cache	undefined	no-cache	immutable
/js/3647.e6884fb5.js	no-cache	undefined	no-cache	immutable
/js/9342.c7b5e54f.js	no-cache	undefined	no-cache	immutable
/js/app.186f7291.js	no-cache	undefined	no-cache	immutable
/js/chunk-vendors.37e8929b.js	no-cache	undefined	no-cache	immutable
/js/component-feedback-button.0447c840.js	no-cache	undefined	no-cache	immutable
/js/component-home-config-section.04391182.js	no-cache	undefined	no-cache	immutable
/js/component-home.0f5945af.js	no-cache	undefined	no-cache	immutable
/js/component-hover-cards.957b7e0e.js	no-cache	undefined	no-cache	immutable
/js/component-outdated-version.17283d89.js	no-cache	undefined	no-cache	immutable
/version.txt	no-cache	undefined	no-cache	revalidate

[matthew-white]

Some of these paths may change after I finish moving Frontend to Vite (getodk/central-frontend#671 - should be done soon). However, the list above makes sense to me. Certain exceptions that are already in the nginx config should use the revalidate strategy (e.g., index.html, version.txt). But most things should use the immutable strategy, in particular anything with a hash in the path.