Localized currency with profile override

[red-one1]

Benefits

• Shows pricing in a region-appropriate currency, improving clarity and conversion for non-USD users.
• Lets users override currency explicitly, which avoids confusing locale heuristics.
• Refreshes FX rates on app restart without requiring API keys.

Architecture

• A server-side rates cache pulls USD-based rates from Frankfurter on startup (Nitro plugin) and exposes them via an internal API.
• The client loads rates once on boot and stores them in memory for formatting.
• Currency resolution order is: profile country -> profile timezone -> browser timezone -> browser language. A profile override short-circuits all heuristics.
• Pricing formatters read from a shared currency utility with fallback static rates if the refresh fails.

Code Changes

• Currency resolution, labels, accepted list, and dynamic rate injection in app/utils/currency.ts.
• New startup fetch + API endpoint for Frankfurter rates in server/plugins/currency-rates.ts and server/api/currency/rates.get.ts.
• Client bootstrap for rates in app/plugins/currency.client.ts.
• Profile settings UI adds currency display + override selector in app/components/profile/BasicSettings.vue.
• Profile API and schema updates to persist with migration prisma/migrations/20260208120500_add_currency_preference/migration.sql.
• Pricing components now use localized formatting in app/components/landing/PricingPlans.vue.

Notes

• If Frankfurter is down, the app falls back to static rates.