feat: 交付官方 Docker 运行时，外观改背景图并下线自定义 CSS/JS

站点/后台分轨背景与用户列表排序一并落地；生产 CORS 改走 SITE_URL，健康检查带版本号。

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/handler/setting.go

@@ -41,8 +41,10 @@ type updateSettingsRequest struct {
 	AttachmentMaxMB      *int      `json:"attachment_max_mb"`
 	AttachmentMaxCount   *int      `json:"attachment_max_count"`
 	ImageMaxMB           *int      `json:"image_max_mb"`
-	CustomCSS            *string   `json:"custom_css"`
-	CustomJS             *string   `json:"custom_js"`
+	BgSiteURL            *string   `json:"bg_site_url"`
+	BgSiteMode           *string   `json:"bg_site_mode"`
+	BgAdminURL           *string   `json:"bg_admin_url"`
+	BgAdminMode          *string   `json:"bg_admin_mode"`
 	TimelineGitImport    *string   `json:"timeline_git_import"` // 超管专用；不进公开 settings / WS 广播
 }
 
@@ -68,8 +70,10 @@ func settingsPayload(saved service.PublicSiteSettings) gin.H {
 		"attachment_max_mb":      saved.AttachmentMaxMB,
 		"attachment_max_count":   saved.AttachmentMaxCount,
 		"image_max_mb":           saved.ImageMaxMB,
-		"custom_css":             saved.CustomCSS,
-		"custom_js":              saved.CustomJS,
+		"bg_site_url":            saved.BgSiteURL,
+		"bg_site_mode":           saved.BgSiteMode,
+		"bg_admin_url":           saved.BgAdminURL,
+		"bg_admin_mode":          saved.BgAdminMode,
 	}
 }
 
@@ -80,8 +84,9 @@ func (req *updateSettingsRequest) hasAny() bool {
 		req.CodeBlockFoldLines != nil || req.UIAnimations != nil || req.AnimCodeFold != nil ||
 		req.AnimSmoothScroll != nil || req.AnimChrome != nil || req.PostLinkNewTab != nil ||
 		req.AttachmentExtLimit != nil || req.AttachmentExts != nil || req.AttachmentMaxMB != nil ||
-		req.AttachmentMaxCount != nil || req.ImageMaxMB != nil || req.CustomCSS != nil ||
-		req.CustomJS != nil || req.TimelineGitImport != nil
+		req.AttachmentMaxCount != nil || req.ImageMaxMB != nil ||
+		req.BgSiteURL != nil || req.BgSiteMode != nil ||
+		req.BgAdminURL != nil || req.BgAdminMode != nil || req.TimelineGitImport != nil
 }
 
 // AdminGetSettings 超管读取站点设置（含 timeline_git_import，不进公开 /api/settings）
@@ -269,20 +274,32 @@ func (h *Handlers) UpdateSettings(c *gin.Context) {
 			return
 		}
 	}
-	if req.CustomCSS != nil {
-		if err := h.Setting.SetCustomCSS(*req.CustomCSS); err != nil {
+	if req.BgSiteURL != nil {
+		if err := h.applyBgURL(service.BgSurfaceSite, *req.BgSiteURL); err != nil {
+			writeBgSettingError(c, err)
+			return
+		}
+	}
+	if req.BgAdminURL != nil {
+		if err := h.applyBgURL(service.BgSurfaceAdmin, *req.BgAdminURL); err != nil {
+			writeBgSettingError(c, err)
+			return
+		}
+	}
+	if req.BgSiteMode != nil {
+		if err := h.Setting.SetBgSiteMode(*req.BgSiteMode); err != nil {
 			if errors.Is(err, service.ErrInvalidSiteSetting) {
-				c.JSON(http.StatusBadRequest, gin.H{"error": "自定义 CSS 过长或含非法闭合标签"})
+				c.JSON(http.StatusBadRequest, gin.H{"error": "无效的背景铺放模式"})
 				return
 			}
 			c.JSON(http.StatusInternalServerError, gin.H{"error": "保存站点设置失败"})
 			return
 		}
 	}
-	if req.CustomJS != nil {
-		if err := h.Setting.SetCustomJS(*req.CustomJS); err != nil {
+	if req.BgAdminMode != nil {
+		if err := h.Setting.SetBgAdminMode(*req.BgAdminMode); err != nil {
 			if errors.Is(err, service.ErrInvalidSiteSetting) {
-				c.JSON(http.StatusBadRequest, gin.H{"error": "自定义 JS 过长或含非法闭合标签"})
+				c.JSON(http.StatusBadRequest, gin.H{"error": "无效的背景铺放模式"})
 				return
 			}
 			c.JSON(http.StatusInternalServerError, gin.H{"error": "保存站点设置失败"})
@@ -318,3 +335,46 @@ func (h *Handlers) UpdateSettings(c *gin.Context) {
 	}
 	c.JSON(http.StatusOK, out)
 }
+
+func writeBgSettingError(c *gin.Context, err error) {
+	if errors.Is(err, service.ErrInvalidSiteSetting) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "背景图地址无效"})
+		return
+	}
+	if errors.Is(err, service.ErrBgFileMissing) {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusInternalServerError, gin.H{"error": "保存站点设置失败"})
+}
+
+// applyBgURL 写入对应轨的背景 URL，并删除不再被引用的旧文件
+func (h *Handlers) applyBgURL(surface, url string) error {
+	u, ok := service.NormalizeBgURL(url)
+	if !ok {
+		return service.ErrInvalidSiteSetting
+	}
+	if u != "" && !h.Upload.BackgroundFileExists(u) {
+		return service.ErrBgFileMissing
+	}
+	oldSite, err := h.Setting.BgSiteURL()
+	if err != nil {
+		return err
+	}
+	oldAdmin, err := h.Setting.BgAdminURL()
+	if err != nil {
+		return err
+	}
+	if surface == service.BgSurfaceAdmin {
+		if err := h.Setting.SetBgAdminURL(u); err != nil {
+			return err
+		}
+		h.Upload.RemoveBackgroundIfUnused(oldAdmin, oldSite, u)
+		return nil
+	}
+	if err := h.Setting.SetBgSiteURL(u); err != nil {
+		return err
+	}
+	h.Upload.RemoveBackgroundIfUnused(oldSite, u, oldAdmin)
+	return nil
+}