chore: performance improvements

[ccev]

Service worker migration

Diadem no longer installs an offline cache because it could delay initial map loading and retain user-specific API
responses. The next deployment serves a one-time cleanup worker that deletes the old caches and unregisters itself.
Make sure /service-worker.js and /_app/version.json are not edge-cached so existing installations receive that
update immediately.

Changes in PR

• Retired broad offline caching with a self-unregistering cleanup worker.
• Disabled new service-worker registration.
• Added public cache policies for config, masterfile, stats, Koji, locale, and icon indexes.
• Added no-store policies for user, feature, and map-response data.
• Skipped auth/session/Koji permission work for strictly public bootstrap routes.
• Parallelized Discord user and guild lookups.
• Removed redundant permission polygons for unrestricted users.
• Started server-settings loading as soon as user details resolve.
• Prevented immediate re-POST of unchanged user settings.
• Ensured first map query waits for effective server settings.
• Reduced background map polling from 5 seconds to 20 seconds.
• Deferred search index construction until search is opened.
• Updated Cloudflare/cache and service-worker migration documentation.