feat(home-banner): 轮播支持 PC/移动两端分图与热区跳转，热区图悬浮放大；修复上传压缩压白透明 PNG

backend/internal/modules/systemconfig/normalize.go

@@ -1,9 +1,14 @@
 package systemconfig
 
 import (
+	"math"
 	"strings"
 )
 
+// 热区悬浮放大倍数：与前端 BANNER_HOTSPOT_DEFAULT_HOVER_SCALE 保持一致。
+const defaultBannerHotspotHoverScale = 1.06
+const maxBannerHotspotHoverScale = 1.5
+
 func normalizeAnnouncements(items []string) []string {
 	normalized := make([]string, 0, len(items))
 	for _, item := range items {
@@ -26,11 +31,15 @@ func normalizeHomeBanners(items []HomeBannerItem) []HomeBannerItem {
 		item.Badge = strings.TrimSpace(item.Badge)
 		item.Pill = strings.TrimSpace(item.Pill)
 		item.Tone = strings.TrimSpace(item.Tone)
-		item.ImageURL = strings.TrimSpace(item.ImageURL)
-		if item.Title == "" && item.ImageURL == "" {
+		// 旧结构只有一张图，两端共用，避免历史配置升级后丢图
+		legacyImageURL := strings.TrimSpace(item.ImageURL)
+		item.ImageURL = ""
+		item.PC = normalizeBannerVisual(item.PC, legacyImageURL)
+		item.Mobile = normalizeBannerVisual(item.Mobile, legacyImageURL)
+		if item.Title == "" && item.PC.ImageURL == "" && item.Mobile.ImageURL == "" {
 			continue
 		}
-		if item.Tone != "green" && item.Tone != "orange" {
+		if item.Tone != "green" && item.Tone != "orange" && item.Tone != "gold" {
 			item.Tone = "blue"
 		}
 		normalized = append(normalized, item)
@@ -41,6 +50,88 @@ func normalizeHomeBanners(items []HomeBannerItem) []HomeBannerItem {
 	return normalized
 }
 
+func normalizeBannerVisual(visual HomeBannerVisual, legacyImageURL string) HomeBannerVisual {
+	visual.ImageURL = strings.TrimSpace(visual.ImageURL)
+	if visual.ImageURL == "" {
+		visual.ImageURL = legacyImageURL
+	}
+	visual.Alt = strings.TrimSpace(visual.Alt)
+	visual.Action = normalizeBannerAction(visual.Action)
+	hotspots := make([]HomeBannerHotspot, 0, len(visual.Hotspots))
+	for _, hotspot := range visual.Hotspots {
+		item, ok := normalizeBannerHotspot(hotspot)
+		if !ok {
+			continue
+		}
+		hotspots = append(hotspots, item)
+	}
+	visual.Hotspots = hotspots
+	return visual
+}
+
+// normalizeBannerHotspot 收敛热区坐标：宽高为 0 的热区无意义直接丢弃，其余保证不越界。
+func normalizeBannerHotspot(hotspot HomeBannerHotspot) (HomeBannerHotspot, bool) {
+	width := clampBannerPercent(hotspot.Width, 100)
+	height := clampBannerPercent(hotspot.Height, 100)
+	if width <= 0 || height <= 0 {
+		return HomeBannerHotspot{}, false
+	}
+	hotspot.ID = strings.TrimSpace(hotspot.ID)
+	hotspot.Label = strings.TrimSpace(hotspot.Label)
+	hotspot.ImageURL = strings.TrimSpace(hotspot.ImageURL)
+	hotspot.HoverScale = normalizeHotspotHoverScale(hotspot.HoverScale)
+	hotspot.Width = width
+	hotspot.Height = height
+	hotspot.X = clampBannerPercent(hotspot.X, 100-width)
+	hotspot.Y = clampBannerPercent(hotspot.Y, 100-height)
+	hotspot.Action = normalizeBannerAction(hotspot.Action)
+	return hotspot, true
+}
+
+// normalizeHotspotHoverScale 悬浮放大倍数：缺失/非法回落默认值，上限 1.5 防止热区盖住整张图。
+func normalizeHotspotHoverScale(value float64) float64 {
+	if value <= 0 {
+		return defaultBannerHotspotHoverScale
+	}
+	if value > maxBannerHotspotHoverScale {
+		value = maxBannerHotspotHoverScale
+	} else if value < 1 {
+		value = 1
+	}
+	return math.Round(value*100) / 100
+}
+
+// normalizeBannerAction 目标缺失的跳转会变成「点了没反应」的死热区，统一退化为 none。
+func normalizeBannerAction(action HomeBannerAction) HomeBannerAction {
+	action.Type = strings.TrimSpace(action.Type)
+	action.Target = strings.TrimSpace(action.Target)
+	switch action.Type {
+	case "route", "link":
+		if action.Target == "" {
+			return HomeBannerAction{Type: "none"}
+		}
+	case "preview":
+		action.Target = ""
+		action.OpenNewTab = false
+	case "none":
+		action.Target = ""
+		action.OpenNewTab = false
+	default:
+		return HomeBannerAction{Type: "none"}
+	}
+	return action
+}
+
+func clampBannerPercent(value float64, max float64) float64 {
+	if value < 0 {
+		value = 0
+	}
+	if value > max {
+		value = max
+	}
+	return math.Round(value*100) / 100
+}
+
 func normalizeOrderAgreements(agreements *OrderAgreementsDTO) {
 	defaults := DefaultOrderAgreements()
 	agreements.VirtualAssetPurchase.Title = strings.TrimSpace(agreements.VirtualAssetPurchase.Title)