Improve ad placement and fix display issues on the homepage

Modify ad insertion logic on the homepage to prevent ads from appearing in the same row and update image URLs in the gallery data.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 517dfa7b-26ac-463d-a6e1-a58c6df97188
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: e238672d-f0b8-42f8-b206-9c933e38a0b7
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/f209e72a-0939-48fa-84fc-57854de71967/517dfa7b-26ac-463d-a6e1-a58c6df97188/nFw7xof
Replit-Helium-Checkpoint-Created: true

client/src/pages/home.tsx

@@ -499,27 +499,28 @@ export default function Home() {
       items.push({ type: "article", key: `a-${shuffled[ai].id}`, article: shuffled[ai++] });
     }
 
-    const adPositions = [3, 9, 17, 23];
-    let adIdx = 0;
-    for (const pos of adPositions) {
-      if (pos <= items.length) {
-        items.splice(pos, 0, { type: "ad", key: `ad-${adIdx++}` });
-      }
-    }
-
     const remainder = items.length % 4;
     if (remainder > 0 && shuffled.length > 0) {
       let fill = 0;
-      const usedIds = new Set(items.filter(i => i.article).map(i => i.article!.id));
-      const fillPool = shuffled.filter(a => !usedIds.has(a.id));
       while (items.length % 4 !== 0) {
-        const src = fillPool.length > 0 ? fillPool : shuffled;
-        const art = src[fill % src.length];
+        const art = shuffled[fill % shuffled.length];
         items.push({ type: "article", key: `fill-${fill}`, article: art });
         fill++;
       }
     }
 
+    const totalRows = items.length / 4;
+    const adRows = [1, 3, 5, 7];
+    const adCols = [3, 1, 2, 0];
+    adRows.forEach((row, i) => {
+      if (row < totalRows) {
+        const idx = row * 4 + adCols[i % adCols.length];
+        if (items[idx] && items[idx].type === "article") {
+          items[idx] = { type: "ad", key: `ad-${i}` };
+        }
+      }
+    });
+
     return items;
   }, [shuffled, widgets]);