feat: make tweet field optional in PostDetailResponse and refactor metadata generation functions

apps/frontend/src/app/detail/[id]/page.tsx

@@ -13,7 +13,7 @@ type PostDetailResponse = {
     url?: string;
     author?: string;
     tags?: string[];
-    tweet: {
+    tweet?: {
         text?: string;
         title?: string;
     };
@@ -37,6 +37,22 @@ function createDetailDescription(post: PostDetailResponse) {
     return `${author} | ${source} post${tagText}`;
 }
 
+function createDetailTitle(post: PostDetailResponse) {
+    const author = post.author?.trim() || "unknown";
+    const source = getSourceLabel(post.type);
+    const rawText = post.type === "twitter" ? post.tweet?.text : post.tweet?.title;
+    const contentText = rawText?.trim() || post._id;
+    return `${author} - ${contentText} | ${source}`;
+}
+
+function toAbsoluteUrl(value: string, baseUrl: string) {
+    try {
+        return new URL(value, baseUrl).toString();
+    } catch {
+        return value;
+    }
+}
+
 
 
 async function getApiBaseUrl() {
@@ -122,12 +138,13 @@ export async function generateMetadata({ params }: { params: Promise<{ id: strin
 
         const source = getSourceLabel(post.type);
         const author = post.author?.trim() || "unknown";
-        const title = `${author} - ${post.type == "twitter" ? post.tweet.text : post.tweet.title} | ${source}`;
+        const title = createDetailTitle(post);
         const description = createDetailDescription(post);
-        const ogImages = post.mediaUrl
+        const ogImageUrl = post.mediaUrl ? toAbsoluteUrl(post.mediaUrl, apiBaseUrl) : undefined;
+        const ogImages = ogImageUrl
             ? [
                 {
-                    url: post.mediaUrl,
+                    url: ogImageUrl,
                     alt: `${author} ${source}`,
                 },
             ]
@@ -151,7 +168,7 @@ export async function generateMetadata({ params }: { params: Promise<{ id: strin
                 card: post.mediaUrl ? "summary_large_image" : "summary",
                 title,
                 description,
-                images: post.mediaUrl ? [post.mediaUrl] : undefined,
+                images: ogImageUrl ? [ogImageUrl] : undefined,
             },
         };
     } catch {