feat: 品牌裁剪弹窗/Markdown 行内短代码与详情视频块等

新增：
- BrandCropModal 品牌图裁剪弹窗 + cropImage 工具
- Markdown 行内短代码（inlineShortcodes + remark 插件）
- MdDetails 折叠块、MdVideo 视频块组件
- directiveBlocks/inlineShortcodes 测试

其它：
- 聊天后端（handler/service chat）调整
- Markdown 渲染链路、编辑器、全局样式与品牌相关面板更新

frontend/app/admin/settings/BrandSeoPanel.tsx

@@ -7,6 +7,7 @@ import {
   AdminSettingsActions,
   AdminSettingsGroup,
 } from "@/components/admin";
+import BrandCropModal from "@/components/BrandCropModal";
 import BrandLockup from "@/components/BrandLockup";
 import { apiBrandFromMedia, apiUpdateSiteSettings, apiUploadBrand, type PublicSettings } from "@/lib/api";
 import {
@@ -15,6 +16,7 @@ import {
   brandAccept,
   brandAliasPath,
   brandFileOk,
+  normalizeBrandURL,
   type BrandLogoFit,
   type BrandLogoSize,
   type BrandMark,
@@ -77,6 +79,9 @@ export default function BrandSeoPanel({
   const [saving, setSaving] = useState(false);
   const [saveError, setSaveError] = useState("");
   const [picker, setPicker] = useState<BrandSlot | null>(null);
+  const [cropSlot, setCropSlot] = useState<BrandSlot | null>(null);
+  const [cropSeedFile, setCropSeedFile] = useState<File | null>(null);
+  const [cropSeedUrl, setCropSeedUrl] = useState("");
   const [copiedSlot, setCopiedSlot] = useState<BrandSlot | null>(null);
   const blobs = useRef<string[]>([]);
   const saveGen = useRef(0);
@@ -123,6 +128,18 @@ export default function BrandSeoPanel({
     return draft.committed;
   };
 
+  const openCrop = (slot: BrandSlot, file: File | null, url: string) => {
+    setCropSlot(slot);
+    setCropSeedFile(file);
+    setCropSeedUrl(url);
+  };
+
+  const closeCrop = () => {
+    setCropSlot(null);
+    setCropSeedFile(null);
+    setCropSeedUrl("");
+  };
+
   const discard = () => {
     [light, dark, favicon].forEach((d) => {
       if (d.blob) URL.revokeObjectURL(d.blob);
@@ -237,8 +254,8 @@ export default function BrandSeoPanel({
             // 预览槽（≤56px 高，宽标可能更宽）：本站图走 160/384 密度变体
             // eslint-disable-next-line @next/next/no-img-element
             <img
-              src={isOwnImage(preview) ? variantURL(preview, pickVariantWidth(160)) : preview}
-              srcSet={isOwnImage(preview) ? densitySrcSet(preview, 160) : undefined}
+              src={isOwnImage(preview) ? variantURL(preview, pickVariantWidth(384)) : preview}
+              srcSet={isOwnImage(preview) ? densitySrcSet(preview, 384) : undefined}
               alt=""
             />
           ) : (
@@ -277,7 +294,14 @@ export default function BrandSeoPanel({
                     toast(err);
                     return;
                   }
-                  replaceFile(slot, file);
+                  // SVG / ICO 无需裁剪，直接走原流程
+                  const isVector = file.name.toLowerCase().endsWith(".svg");
+                  const isIco = file.name.toLowerCase().endsWith(".ico");
+                  if (isVector || isIco) {
+                    replaceFile(slot, file);
+                    return;
+                  }
+                  openCrop(slot, file, "");
                 }}
               />
             </label>
@@ -418,11 +442,50 @@ export default function BrandSeoPanel({
         onClose={() => setPicker(null)}
         onPick={(item) => {
           if (!picker) return;
-          const [prev, set] = drafts[picker];
-          if (prev.blob) URL.revokeObjectURL(prev.blob);
-          set({ ...prev, file: null, blob: "", mediaId: item.id, mediaUrl: item.url });
+          const slot = picker;
+          setPicker(null);
+          // 已是品牌目录的历史图（含裁剪产物）：直接引用，不再复制
+          const brandURL = normalizeBrandURL(slot, item.url);
+          if (brandURL) {
+            const [prev, set] = drafts[slot];
+            if (prev.blob) URL.revokeObjectURL(prev.blob);
+            set({ committed: brandURL, file: null, blob: "", mediaId: null, mediaUrl: "" });
+            return;
+          }
+          const lower = item.url.toLowerCase();
+          const isVector = lower.endsWith(".svg");
+          const isIco = lower.endsWith(".ico");
+          // SVG / ICO 不可裁剪，复制一份进品牌目录后引用
+          if ((isVector || isIco) && item.attachmentId != null) {
+            const [prev, set] = drafts[slot];
+            if (prev.blob) URL.revokeObjectURL(prev.blob);
+            set({ ...prev, file: null, blob: "", mediaId: item.attachmentId, mediaUrl: item.url });
+            return;
+          }
+          openCrop(slot, null, item.url);
         }}
       />
+      {cropSlot ? (
+        <BrandCropModal
+          open
+          slot={cropSlot}
+          seedFile={cropSeedFile}
+          seedUrl={cropSeedUrl}
+          onClose={closeCrop}
+          onSeedConsumed={() => {
+            setCropSeedFile(null);
+            setCropSeedUrl("");
+          }}
+          onCropped={(url) => {
+            const [, set] = drafts[cropSlot];
+            set((prev) => {
+              if (prev.blob) URL.revokeObjectURL(prev.blob);
+              return { committed: url, file: null, blob: "", mediaId: null, mediaUrl: "" };
+            });
+            closeCrop();
+          }}
+        />
+      ) : null}
     </AdminSettingsGroup>
   );
 }