Multi-Currency Tracker

Build a multi-currency position tracker with PostgreSQL:
1. Currency positions list (currency code, amount, USD equivalent)
2. Add/update position form
3. Exchange rate table (manually entered rates)
4. Total portfolio value in USD
5. Currency exposure pie chart
6. Gain/loss calculation vs. original cost basis

Database: currency_positions (id, currency_code, amount, cost_basis_usd, acquisition_date), exchange_rates (id, from_currency, to_currency, rate, date). Seed with 5 currencies and historical rates.