feat: 页脚优先展示后台配置的页脚 Logo

- CmsSiteInfo 加 websiteFooterLogo 类型
- useSite 新增 siteFooterLogo(websiteFooterLogo 优先，回退
  siteLogo)；siteLogo/siteFooterLogo 统一过 ensureFullUrl，
  兼容本地存储相对路径(/api/file 代理)与完整 OSS URL
- template-01~08/10 共 9 个模板 Footer 的 SiteBrand 改用
  siteFooterLogo；template-09 页脚无品牌区保持不变
- 未配置页脚 Logo 时行为与旧版完全一致(回退站点 Logo)

app/templates/template-10/components/Footer.vue

@@ -7,7 +7,7 @@
         <div class="lg:col-span-2">
           <SiteBrand
             link-class="inline-flex items-center gap-2 mb-5"
-            :logo="siteLogo"
+            :logo="siteFooterLogo"
             :icon="siteIcon"
             :name="siteName"
             logo-class="h-[44px] w-auto max-w-[220px] object-contain brightness-0 invert"
@@ -104,7 +104,7 @@
 import type { CmsNavigation } from '~/types'
 
 const {
-  siteInfo, siteName, siteLogo, siteIcon,
+  siteInfo, siteName, siteLogo, siteFooterLogo, siteIcon,
   phone, email, address, copyright, icpNo,
   navigations, allNavigations, fetchSiteInfo
 } = useSite()