feat: 更新管理端品牌 Logo 体系

- 替换主标、暗色主标、收起图标、单色版与 favicon 资源

- 新增暗色收起图标接入能力，补齐公共 logo 配置回退链路

- 增加品牌预览页，集中展示浅色、黑场和应用场景效果

easyflow-ui-admin/packages/effects/layouts/src/basic/layout.vue

@@ -261,6 +261,13 @@ const headerSlots = computed(() => {
         :src="preferences.logo.source"
         :src-dark="preferences.logo.sourceDark ?? preferences.logo.source ?? ''"
         :src-mini="preferences.logo.sourceMini ?? preferences.logo.source ?? ''"
+        :src-mini-dark="
+          preferences.logo.sourceMiniDark ??
+          preferences.logo.sourceMini ??
+          preferences.logo.sourceDark ??
+          preferences.logo.source ??
+          ''
+        "
         :text="preferences.app.name ?? ''"
         :theme="showHeaderNav ? headerTheme : theme"
         @click="clickLogo"
@@ -355,6 +362,13 @@ const headerSlots = computed(() => {
         :src="preferences.logo.source"
         :src-dark="preferences.logo.sourceDark ?? preferences.logo.source ?? ''"
         :src-mini="preferences.logo.sourceMini ?? preferences.logo.source ?? ''"
+        :src-mini-dark="
+          preferences.logo.sourceMiniDark ??
+          preferences.logo.sourceMini ??
+          preferences.logo.sourceDark ??
+          preferences.logo.source ??
+          ''
+        "
         :text="preferences.app.name ?? ''"
         :theme="theme"
       >