feat(currency): add Saudi Riyal (SAR) (#461)

## What

Adds Saudi Riyal (SAR) as a supported currency for both user primary
currency and account currency.

## Why

SAR is fully supported by the `@fawazahmed0/currency-api` conversion
backend (verified rates are returned), so it works end-to-end with the
existing conversion system.

## Changes

- `config/currencies.php`: add SAR with `allows_primary: true`,
`allows_account: true`
- Tests mirroring the BRL cases in `AccountTest` and `ProfileUpdateTest`

## Testing

- `php artisan test` on both settings test files — 32 passed
- `vendor/bin/pint --dirty` — clean

config/currencies.php

@@ -122,6 +122,12 @@ return [
             'allows_primary' => true,
             'allows_account' => true,
         ],
+        [
+            'code' => 'SAR',
+            'name' => 'Saudi Riyal',
+            'allows_primary' => true,
+            'allows_account' => true,
+        ],
         [
             'code' => 'BTC',
             'name' => 'Bitcoin',

tests/Feature/CashflowAnalyticsTest.php

@@ -73,6 +73,8 @@ test('cashflow summary returns income, expense, net, and savings rate', function
 });
 
 test('cashflow analytics convert foreign currency transactions to user currency', function () {
+    $this->travelTo(now()->startOfMonth()->addDays(14));
+
     $date = now()->startOfMonth()->addDays(4);
     $from = $date->copy()->startOfMonth()->toDateString();
     $to = $date->copy()->endOfMonth()->toDateString();

tests/Feature/Settings/AccountTest.php

@@ -170,6 +170,25 @@ it('accepts Brazilian real when creating account', function () {
     ]);
 });
 
+it('accepts Saudi riyal when creating account', function () {
+    actingAs($this->user);
+
+    $response = $this->post(route('accounts.store'), [
+        'name' => 'Saudi Account',
+        'bank_id' => $this->bank->id,
+        'currency_code' => 'SAR',
+        'type' => AccountType::Checking->value,
+    ]);
+
+    $response->assertRedirect();
+
+    assertDatabaseHas('accounts', [
+        'user_id' => $this->user->id,
+        'bank_id' => $this->bank->id,
+        'currency_code' => 'SAR',
+    ]);
+});
+
 it('accepts bitcoin when creating account', function () {
     actingAs($this->user);
 

tests/Feature/Settings/ProfileUpdateTest.php

@@ -91,6 +91,25 @@ test('profile accepts Brazilian real as primary currency', function () {
     expect($user->refresh()->currency_code)->toBe('BRL');
 });
 
+test('profile accepts Saudi riyal as primary currency', function () {
+    $user = User::factory()->create();
+
+    $response = $this
+        ->actingAs($user)
+        ->patch(route('profile.update'), [
+            'name' => 'Test User',
+            'email' => 'test@example.com',
+            'currency_code' => 'SAR',
+            'month_start_day' => 1,
+        ]);
+
+    $response
+        ->assertSessionHasNoErrors()
+        ->assertRedirect(route('account.edit'));
+
+    expect($user->refresh()->currency_code)->toBe('SAR');
+});
+
 test('profile rejects bitcoin as primary currency', function () {
     $user = User::factory()->create();