feat(#18): import de extratos OFX e CSV — parser, dedup, preview e confirmação

Parser OFX tolerante ao formato SGML de bancos brasileiros (sem closing tags, BOM,
timezone suffix). Parser CSV com separador de campo/decimal configurável. Dedup por
FITID (OFX) ou date+amount+desc normalizado. Fluxo: POST /preview → revisão na UI
→ POST /confirm salva e loga. Migration 002 adiciona external_id com unique index.

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

apps/api/internal/repository/transaction.go

@@ -0,0 +1,83 @@
+package repository
+
+import (
+	"context"
+	"strings"
+
+	"github.com/jackc/pgx/v5/pgxpool"
+
+	"financeiro-carvalho/internal/model"
+)
+
+type TransactionRepository interface {
+	IsDuplicate(ctx context.Context, date, description string, amount float64) (bool, error)
+	IsExternalIDKnown(ctx context.Context, externalID string) (bool, error)
+	BulkInsert(ctx context.Context, rows []model.ImportRow) (int, error)
+	SaveImportLog(ctx context.Context, filename, format string, imported, duplicates, errors int) error
+}
+
+type transactionRepo struct{ db *pgxpool.Pool }
+
+func NewTransactionRepository(db *pgxpool.Pool) TransactionRepository {
+	return &transactionRepo{db: db}
+}
+
+// normalizeDesc lowercases and collapses whitespace for fuzzy dedup.
+func normalizeDesc(s string) string {
+	return strings.ToLower(strings.Join(strings.Fields(s), " "))
+}
+
+func (r *transactionRepo) IsDuplicate(ctx context.Context, date, description string, amount float64) (bool, error) {
+	var count int
+	err := r.db.QueryRow(ctx, `
+		SELECT COUNT(*) FROM transactions
+		WHERE date = $1 AND amount = $2 AND LOWER(description) = $3`,
+		date, amount, normalizeDesc(description)).Scan(&count)
+	return count > 0, err
+}
+
+func (r *transactionRepo) IsExternalIDKnown(ctx context.Context, externalID string) (bool, error) {
+	if externalID == "" {
+		return false, nil
+	}
+	var count int
+	err := r.db.QueryRow(ctx, `
+		SELECT COUNT(*) FROM transactions WHERE external_id = $1`, externalID).Scan(&count)
+	return count > 0, err
+}
+
+func (r *transactionRepo) BulkInsert(ctx context.Context, rows []model.ImportRow) (int, error) {
+	tx, err := r.db.Begin(ctx)
+	if err != nil {
+		return 0, err
+	}
+	defer tx.Rollback(ctx)
+
+	count := 0
+	for _, row := range rows {
+		if row.IsDuplicate {
+			continue
+		}
+		var extID *string
+		if row.ExternalID != "" {
+			extID = &row.ExternalID
+		}
+		_, err := tx.Exec(ctx, `
+			INSERT INTO transactions (date, amount, description, type, source, external_id)
+			VALUES ($1, $2, $3, $4, 'import', $5)`,
+			row.Date, row.Amount, row.Description, row.Type, extID)
+		if err != nil {
+			return count, err
+		}
+		count++
+	}
+	return count, tx.Commit(ctx)
+}
+
+func (r *transactionRepo) SaveImportLog(ctx context.Context, filename, format string, imported, duplicates, errors int) error {
+	_, err := r.db.Exec(ctx, `
+		INSERT INTO import_logs (filename, format, imported_count, duplicate_count, error_count)
+		VALUES ($1, $2, $3, $4, $5)`,
+		filename, format, imported, duplicates, errors)
+	return err
+}