feat(ai-cases): 성공 사례 카드에 PDF 첫 슬라이드 썸네일·그라데이션 개선

- 목록에서 슬라이드 워밍(최대 24건) 후 coverImageUrl 전달
- 카드 상단 풀너비 이미지+스크림, 무이미지 시 다층 그라데이션

Made-with: Cursor

server.js

@@ -1189,21 +1189,43 @@ pageRouter.get("/ai-cases/write", (req, res) => {
   });
 });
 
-pageRouter.get("/ai-cases", (req, res) => {
-  const q = (req.query.q || "").trim();
-  const tag = (req.query.tag || "").trim();
-  const meta = loadAiSuccessStoriesMeta();
-  const filtered = filterAiSuccessStories(meta, q, tag);
-  const tags = allAiSuccessStoryTags(meta);
-  res.render("ai-cases", {
-    activeMenu: "ai-cases",
-    adminMode: res.locals.adminMode,
-    opsUserEmail: !!res.locals.opsUserEmail,
-    successStoryDetailAllowed: isAiSuccessStoryDetailAllowed(req, res),
-    stories: filtered,
-    filters: { q, tag },
-    availableTags: tags,
-  });
+pageRouter.get("/ai-cases", async (req, res, next) => {
+  try {
+    const q = (req.query.q || "").trim();
+    const tag = (req.query.tag || "").trim();
+    const meta = loadAiSuccessStoriesMeta();
+    const filtered = filterAiSuccessStories(meta, q, tag);
+    const tags = allAiSuccessStoryTags(meta);
+    /** 목록에서도 카드 썸네일을 쓰기 위해 PDF→슬라이드가 없으면 생성 시도(상세와 동일 소스) */
+    await Promise.all(
+      filtered.slice(0, 24).map(async (m) => {
+        const pdfUrl = (m.pdfUrl || "").trim();
+        if (!pdfUrl) return;
+        if (getAiSuccessSlideImageUrls(m.slug).length > 0) return;
+        try {
+          await ensureAiSuccessStorySlides(m.slug, pdfUrl);
+        } catch (err) {
+          console.warn("[ai-cases] 슬라이드 워밍 실패:", m.slug, err?.message || err);
+        }
+      })
+    );
+    const stories = filtered.map((m) => {
+      const slideUrls = getAiSuccessSlideImageUrls(m.slug);
+      const coverImageUrl = slideUrls.length > 0 ? slideUrls[0] : "";
+      return { ...m, coverImageUrl };
+    });
+    res.render("ai-cases", {
+      activeMenu: "ai-cases",
+      adminMode: res.locals.adminMode,
+      opsUserEmail: !!res.locals.opsUserEmail,
+      successStoryDetailAllowed: isAiSuccessStoryDetailAllowed(req, res),
+      stories,
+      filters: { q, tag },
+      availableTags: tags,
+    });
+  } catch (err) {
+    next(err);
+  }
 });
 
 pageRouter.get("/ai-cases/:slug", async (req, res, next) => {