feat: Add chat embeds v1

Youtube and Website metadata embeds

server/src/routes/proxy.ts

@@ -1,4 +1,5 @@
 import { Router } from 'express';
+import { resolveAndValidateHost, safeFetch } from './ssrf-guard';
 
 const router = Router();
 
@@ -10,14 +11,20 @@ router.get('/image-proxy', async (req, res) => {
       return res.status(400).json({ error: 'Invalid URL' });
     }
 
+    const hostAllowed = await resolveAndValidateHost(url);
+
+    if (!hostAllowed) {
+      return res.status(400).json({ error: 'URL resolves to a blocked address' });
+    }
+
     const controller = new AbortController();
     const timeout = setTimeout(() => controller.abort(), 8000);
-    const response = await fetch(url, { redirect: 'follow', signal: controller.signal });
+    const response = await safeFetch(url, { signal: controller.signal });
 
     clearTimeout(timeout);
 
-    if (!response.ok) {
-      return res.status(response.status).end();
+    if (!response || !response.ok) {
+      return res.status(response?.status ?? 502).end();
     }
 
     const contentType = response.headers.get('content-type') || '';