feat(#21): contas bancárias e patrimônio consolidado

CRUD de contas (corrente/poupança/investimento/cartão) com saldo calculado
automaticamente. account_id nullable em transactions. Widget patrimônio no
dashboard. Tela /contas. Seletor de conta nas transações manuais.

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

apps/api/internal/model/account.go

@@ -0,0 +1,17 @@
+package model
+
+type Account struct {
+	ID             int     `json:"id"`
+	Name           string  `json:"name"`
+	Type           string  `json:"type"`
+	InitialBalance float64 `json:"initial_balance"`
+	Balance        float64 `json:"balance"`
+	CreatedAt      string  `json:"created_at"`
+	UpdatedAt      string  `json:"updated_at"`
+}
+
+type AccountInput struct {
+	Name           string  `json:"name"`
+	Type           string  `json:"type"`
+	InitialBalance float64 `json:"initial_balance"`
+}

apps/api/internal/model/dashboard.go

@@ -28,6 +28,7 @@ type DashboardData struct {
 	TotalIncome        float64             `json:"total_income"`
 	TotalExpenses      float64             `json:"total_expenses"`
 	SavingsPct         float64             `json:"savings_pct"`
+	TotalPatrimony     float64             `json:"total_patrimony"`
 	ByCategory         []CategoryTotal     `json:"by_category"`
 	MonthlyEvolution   []MonthEvolution    `json:"monthly_evolution"`
 	RecentTransactions []RecentTransaction `json:"recent_transactions"`

apps/api/internal/model/transaction.go

@@ -10,6 +10,7 @@ type Transaction struct {
 	Type        string    `json:"type"`       // income | expense
 	Source      string    `json:"source"`     // manual | import
 	CategoryID  *int      `json:"category_id"`
+	AccountID   *int      `json:"account_id"`
 	CreatedAt   time.Time `json:"created_at"`
 	UpdatedAt   time.Time `json:"updated_at"`
 }