refactor(PostCard, ImageGrid, SmartImage): enhance post editing display and image handling

- Introduced a new method to determine the last edited time for posts, prioritizing content_edited_at for better accuracy in display.
- Updated PostCard and PostDetailScreen components to utilize the new editing display logic.
- Enhanced ImageGrid and SmartImage components to support additional preview URLs and improve image loading behavior, including lazy loading optimizations for web.
- Modified Post and PostDTO interfaces to include contentEditedAt for better tracking of post edits.

src/screens/home/PostDetailScreen.tsx

@@ -318,12 +318,23 @@ export const PostDetailScreen: React.FC = () => {
     return formatDateTime(dateString);
   };
 
-  const isPostEdited = (createdAt?: string, updatedAt?: string): boolean => {
-    if (!createdAt || !updatedAt) return false;
-    const created = new Date(createdAt).getTime();
-    const updated = new Date(updatedAt).getTime();
-    if (Number.isNaN(created) || Number.isNaN(updated)) return false;
-    return updated-created > 1000;
+  const getPostEditedDisplayAt = (
+    createdAt?: string | null,
+    contentEditedAt?: string | null,
+    updatedAt?: string | null,
+  ): string | null => {
+    if (contentEditedAt) {
+      const c = new Date(createdAt || '').getTime();
+      const e = new Date(contentEditedAt).getTime();
+      if (!Number.isNaN(c) && !Number.isNaN(e) && e - c > 1000) return contentEditedAt;
+      return null;
+    }
+    if (createdAt && updatedAt) {
+      const c = new Date(createdAt).getTime();
+      const u = new Date(updatedAt).getTime();
+      if (!Number.isNaN(c) && !Number.isNaN(u) && u - c > 1000) return updatedAt;
+    }
+    return null;
   };
 
   // 格式化数字
@@ -1081,14 +1092,21 @@ export const PostDetailScreen: React.FC = () => {
             <Text variant="caption" color={colors.text.hint} style={styles.metaInfoText}>
               发布 {formatRelativeTime(post.created_at)}
             </Text>
-            {isPostEdited(post.created_at, post.updated_at) && (
+            {(() => {
+              const editedAt = getPostEditedDisplayAt(
+                post.created_at,
+                post.content_edited_at,
+                post.updated_at,
+              );
+              return editedAt ? (
               <>
                 <Text style={styles.metaInfoDot}>·</Text>
                 <Text variant="caption" color={colors.text.hint} style={styles.metaInfoText}>
-                  修改 {formatRelativeTime(post.updated_at)}
+                  修改 {formatRelativeTime(editedAt)}
                 </Text>
               </>
-            )}
+              ) : null;
+            })()}
             {post.views_count !== undefined && post.views_count > 0 && (
               <>
                 <Text style={styles.metaInfoDot}>·</Text>