feat: launcher.exe와 game.zip 별도 업로드/서빙 분리

- POST /api/download/upload/game - 게임 zip 업로드
- POST /api/download/upload/launcher - launcher.exe 업로드
- GET /api/download/launcher - launcher.exe 서빙
- Info 모델에 LauncherURL, LauncherSize 필드 추가
- Content-Disposition 헤더로 올바른 파일명 설정

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/download/handler.go

@@ -45,5 +45,29 @@ func (h *Handler) ServeFile(c *fiber.Ctx) error {
 	if _, err := os.Stat(path); err != nil {
 		return c.Status(fiber.StatusNotFound).JSON(fiber.Map{"error": "파일이 없습니다"})
 	}
+	info, _ := h.svc.GetInfo()
+	filename := "game.zip"
+	if info != nil && info.FileName != "" {
+		filename = info.FileName
+	}
+	c.Set("Content-Disposition", `attachment; filename="`+filename+`"`)
+	return c.SendFile(path)
+}
+
+func (h *Handler) UploadLauncher(c *fiber.Ctx) error {
+	body := c.Request().BodyStream()
+	info, err := h.svc.UploadLauncher(body, h.baseURL)
+	if err != nil {
+		return c.Status(fiber.StatusInternalServerError).JSON(fiber.Map{"error": "업로드 실패: " + err.Error()})
+	}
+	return c.JSON(info)
+}
+
+func (h *Handler) ServeLauncher(c *fiber.Ctx) error {
+	path := h.svc.LauncherFilePath()
+	if _, err := os.Stat(path); err != nil {
+		return c.Status(fiber.StatusNotFound).JSON(fiber.Map{"error": "파일이 없습니다"})
+	}
+	c.Set("Content-Disposition", `attachment; filename="launcher.exe"`)
 	return c.SendFile(path)
 }

internal/download/model.go

@@ -15,5 +15,7 @@ type Info struct {
 	Version   string         `json:"version"  gorm:"not null"`
 	FileName  string         `json:"fileName" gorm:"not null"`
 	FileSize  string         `json:"fileSize" gorm:"not null"`
-	FileHash  string         `json:"fileHash" gorm:"not null;default:''"`
+	FileHash     string         `json:"fileHash"     gorm:"not null;default:''"`
+	LauncherURL  string         `json:"launcherUrl"  gorm:"not null;default:''"`
+	LauncherSize string         `json:"launcherSize" gorm:"not null;default:''"`
 }

internal/download/service.go

@@ -31,6 +31,49 @@ func (s *Service) GameFilePath() string {
 	return filepath.Join(s.gameDir, "game.zip")
 }
 
+func (s *Service) LauncherFilePath() string {
+	return filepath.Join(s.gameDir, "launcher.exe")
+}
+
+func (s *Service) UploadLauncher(body io.Reader, baseURL string) (*Info, error) {
+	if err := os.MkdirAll(s.gameDir, 0755); err != nil {
+		return nil, fmt.Errorf("디렉토리 생성 실패: %w", err)
+	}
+
+	finalPath := s.LauncherFilePath()
+	tmpPath := finalPath + ".tmp"
+
+	f, err := os.Create(tmpPath)
+	if err != nil {
+		return nil, fmt.Errorf("파일 생성 실패: %w", err)
+	}
+
+	n, err := io.Copy(f, body)
+	f.Close()
+	if err != nil {
+		os.Remove(tmpPath)
+		return nil, fmt.Errorf("파일 저장 실패: %w", err)
+	}
+
+	if err := os.Rename(tmpPath, finalPath); err != nil {
+		os.Remove(tmpPath)
+		return nil, fmt.Errorf("파일 이동 실패: %w", err)
+	}
+
+	launcherSize := ""
+	if n > 0 {
+		launcherSize = fmt.Sprintf("%.1f MB", float64(n)/1024/1024)
+	}
+
+	info, err := s.repo.GetLatest()
+	if err != nil {
+		info = &Info{}
+	}
+	info.LauncherURL = baseURL + "/api/download/launcher"
+	info.LauncherSize = launcherSize
+	return info, s.repo.Save(info)
+}
+
 // Upload streams the body directly to disk, then extracts metadata from the zip.
 func (s *Service) Upload(filename string, body io.Reader, baseURL string) (*Info, error) {
 	if err := os.MkdirAll(s.gameDir, 0755); err != nil {