## Summary
- **Bug fix:** Dashboard and accounts index cards displayed the
account's original currency code (e.g. `BTC`) even though balances were
already converted to the user's currency (e.g. `EUR`). Now passes
`displayCurrencyCode` to card components so the label matches the
converted amount.
- **Feature:** Added a currency toggle on the account detail chart to
switch between the account's native currency and the user's main
currency. Extends the balance evolution APIs with `display_*` fields
when conversion applies.
- **First-account restriction:** Restricts first-account creation to
primary (fiat) currencies only, ensuring the user's base currency is
always widely supported.
## Changes
### Bug fix — currency label on cards
- `AccountBalanceCard` / `AccountListCard`: Added `displayCurrencyCode`
prop; all amount renders now use it instead of `account.currency_code`
- `dashboard.tsx`: Passes `netWorthEvolution.currency_code` as
`displayCurrencyCode`
- `Accounts/Index.tsx`: Passes `auth.user.currency_code` as
`displayCurrencyCode`
### Backend — API extension
- `DashboardAnalyticsController`: Both `accountBalanceEvolution()` and
`accountDailyBalanceEvolution()` now return `display_value`,
`display_invested_amount`, `display_mortgage_balance` per data point and
a top-level `display_currency_code` when the account currency differs
from the user's
### Frontend — currency toggle
- New `ChartCurrencyToggle` component with `ToggleGroup` showing
currency code labels (e.g. `BTC` / `EUR`)
- `ChartSettingsPopover`: Extended with optional `currencyToggle` prop
for mobile
- `AccountBalanceChart`: Full integration — all amounts, trends,
tooltips, MoM chart, and equity swap to `display_*` values when toggle
is set to user currency
### First-account currency restriction
- `StoreAccountRequest`: First account limited to primary currency codes
- `AccountForm` / `CreateAccountDialog` / `StepCreateAccount`: Pass
`usePrimaryCurrenciesOnly` when applicable
### Tests
- 5 new Pest tests for `display_*` fields in balance evolution endpoints
- 3 new Vitest tests for `deriveAccountMetrics` (mixed-currency, empty
data, invested amounts)
- 1 new Pest test for first-account BTC rejection
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