feat: wallet private key export API with password verification

internal/chain/handler.go

@@ -3,6 +3,7 @@ package chain
 import (
 	"errors"
 	"log"
+	"log/slog"
 	"strconv"
 	"strings"
 
@@ -620,6 +621,39 @@ func (h *Handler) RegisterTemplate(c *fiber.Ctx) error {
 	return c.Status(fiber.StatusCreated).JSON(result)
 }
 
+// ExportWallet godoc
+// @Summary      개인키 내보내기
+// @Description  비밀번호 확인 후 현재 유저의 지갑 개인키를 반환합니다
+// @Tags         Chain
+// @Accept       json
+// @Produce      json
+// @Security     BearerAuth
+// @Param        body  body  exportRequest  true  "비밀번호"
+// @Success      200  {object}  map[string]string
+// @Failure      400  {object}  docs.ErrorResponse
+// @Failure      401  {object}  docs.ErrorResponse
+// @Router       /api/chain/wallet/export [post]
+type exportRequest struct {
+	Password string `json:"password"`
+}
+
+func (h *Handler) ExportWallet(c *fiber.Ctx) error {
+	userID, err := getUserID(c)
+	if err != nil {
+		return err
+	}
+	var req exportRequest
+	if err := c.BodyParser(&req); err != nil || req.Password == "" {
+		return c.Status(400).JSON(fiber.Map{"error": "password is required"})
+	}
+	slog.Warn("wallet export requested", "userID", userID, "ip", c.IP())
+	privKeyHex, err := h.svc.ExportPrivKey(userID, req.Password)
+	if err != nil {
+		return c.Status(401).JSON(fiber.Map{"error": "invalid password"})
+	}
+	return c.JSON(fiber.Map{"privateKey": privKeyHex})
+}
+
 // ---- Internal Handlers (game server, username-based) ----
 
 // InternalGrantReward godoc