feat(#37): módulo de cartão de crédito com faturas mensais

- Migration 011: closing_day/due_day em accounts + tabela credit_bills
- CreditBillService: cria/atualiza fatura corrente on-demand no GET /accounts
- Widget FATURA ATUAL no dashboard com total e botão PAGAR
- AccountsView: campos closing_day/due_day para contas credit + painel fatura
- Dashboard: current_bills lista faturas não pagas de todos os cartões

Co-Authored-By: Claude Sonnet 4.6 <[email protected]>

apps/api/internal/model/account.go

@@ -8,6 +8,9 @@ type Account struct {
 	Balance        float64 `json:"balance"`
 	YieldType      string  `json:"yield_type"` // "none" | "cdi" | "variable"
 	LastYieldDate  *string `json:"last_yield_date,omitempty"`
+	ClosingDay     *int    `json:"closing_day,omitempty"`
+	DueDay         *int    `json:"due_day,omitempty"`
+	CurrentBill    *CreditBill `json:"current_bill,omitempty"`
 	CreatedAt      string  `json:"created_at"`
 	UpdatedAt      string  `json:"updated_at"`
 }
@@ -17,4 +20,6 @@ type AccountInput struct {
 	Type           string  `json:"type"`
 	InitialBalance float64 `json:"initial_balance"`
 	YieldType      string  `json:"yield_type"` // "none" | "cdi" | "variable"
+	ClosingDay     *int    `json:"closing_day,omitempty"`
+	DueDay         *int    `json:"due_day,omitempty"`
 }

apps/api/internal/model/credit_bill.go

@@ -0,0 +1,22 @@
+package model
+
+type CreditBill struct {
+	ID                int     `json:"id"`
+	AccountID         int     `json:"account_id"`
+	AccountName       string  `json:"account_name"`
+	PeriodStart       string  `json:"period_start"`
+	PeriodEnd         string  `json:"period_end"`
+	DueDate           string  `json:"due_date"`
+	Total             float64 `json:"total"`
+	Paid              bool    `json:"paid"`
+	PaidAt            *string `json:"paid_at,omitempty"`
+	PaymentAccountID  *int    `json:"payment_account_id,omitempty"`
+}
+
+type CreditBillInput struct {
+	AccountID         int    `json:"account_id"`
+	PeriodStart       string `json:"period_start"`
+	PeriodEnd         string `json:"period_end"`
+	DueDate           string `json:"due_date"`
+	PaymentAccountID  *int   `json:"payment_account_id,omitempty"`
+}

apps/api/internal/model/dashboard.go

@@ -34,4 +34,5 @@ type DashboardData struct {
 	RecentTransactions      []RecentTransaction `json:"recent_transactions"`
 	PendingRecurring        int                 `json:"pending_recurring"`
 	PendingIncomeRecurrings []PendingIncome     `json:"pending_income_recurrings"`
+	CurrentBills            []CreditBill        `json:"current_bills"`
 }