feat: 添加核心财务模型、账户存储库和存钱罐服务

internal/models/models.go

@@ -286,11 +286,16 @@ func (Account) TableName() string {
 	return "accounts"
 }
 
+// TotalBalance calculates the total balance including sub-accounts
+// Feature: financial-core-upgrade
+// Validates: Requirements 1.3
 // TotalBalance calculates the total balance including sub-accounts
 // Feature: financial-core-upgrade
 // Validates: Requirements 1.3
 func (a *Account) TotalBalance() float64 {
-	total := a.AvailableBalance + a.FrozenBalance
+	// Balance is treated as Available Balance (liquid funds)
+	// FrozenBalance represents funds locked in savings pots/piggy banks
+	total := a.Balance + a.FrozenBalance
 	for _, sub := range a.SubAccounts {
 		if sub.SubAccountType != nil && *sub.SubAccountType != SubAccountTypeSavingsPot {
 			total += sub.Balance