Profile avatar için cache eklendi

server/server.js

@@ -232,8 +232,17 @@ app.get("/api/profile/avatar", requireAuth, (req, res) => {
   if (!fs.existsSync(AVATAR_PATH)) {
     return res.status(404).json({ error: "Avatar bulunamadı" });
   }
+  const stat = fs.statSync(AVATAR_PATH);
+  const etag = `W/"${stat.size}-${stat.mtimeMs}"`;
+
+  if (req.headers["if-none-match"] === etag) {
+    return res.status(304).end();
+  }
+
   res.setHeader("Content-Type", "image/png");
-  res.setHeader("Cache-Control", "no-store");
+  res.setHeader("Cache-Control", "public, max-age=2592000, stale-while-revalidate=86400");
+  res.setHeader("ETag", etag);
+  res.setHeader("Last-Modified", stat.mtime.toUTCString());
   fs.createReadStream(AVATAR_PATH).pipe(res);
 });