feat: add image proxy route and integrate it into media handling for improved Twitter content fetching

apps/backend/src/routes/proxy.ts

@@ -0,0 +1,45 @@
+import { Elysia, t } from "elysia";
+
+const ALLOWED_HOSTS = [
+    "pbs.twimg.com",
+    "video.twimg.com",
+    "ton.twimg.com",
+    "abs.twimg.com",
+];
+
+export default new Elysia({ prefix: "/proxy" })
+    .get("/image", async ({ query, status, set }) => {
+        const targetUrl = query.url;
+
+        let parsed: URL;
+        try {
+            parsed = new URL(targetUrl);
+        } catch {
+            return status(400, "Invalid URL");
+        }
+
+        if (!ALLOWED_HOSTS.includes(parsed.hostname)) {
+            return status(403, `Host not allowed: ${parsed.hostname}`);
+        }
+
+        const response = await fetch(targetUrl, {
+            headers: {
+                "User-Agent": "Mozilla/5.0 (compatible; bot/1.0)",
+                "Referer": "https://twitter.com/",
+            },
+        });
+
+        if (!response.ok) {
+            return status(response.status as any, `Upstream error: ${response.status}`);
+        }
+
+        const contentType = response.headers.get("content-type") ?? "application/octet-stream";
+        set.headers["Content-Type"] = contentType;
+        set.headers["Cache-Control"] = "public, max-age=86400, immutable";
+
+        return response;
+    }, {
+        query: t.Object({
+            url: t.String(),
+        }),
+    });