Display a banner for unsupported Zulip Server versions.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

app/main/request.ts

@@ -71,11 +71,19 @@ export const _getServerSettings = async (
 
   const data: unknown = JSON.parse(await getStream(response));
   /* eslint-disable @typescript-eslint/naming-convention */
-  const {realm_name, realm_uri, realm_icon} = z
+  const {
+    realm_name,
+    realm_uri,
+    realm_icon,
+    zulip_version,
+    zulip_feature_level,
+  } = z
     .object({
       realm_name: z.string(),
-      realm_uri: z.string(),
+      realm_uri: z.string().url(),
       realm_icon: z.string(),
+      zulip_version: z.string().default("unknown"),
+      zulip_feature_level: z.number().default(0),
     })
     .parse(data);
   /* eslint-enable @typescript-eslint/naming-convention */
@@ -86,6 +94,8 @@ export const _getServerSettings = async (
     icon: realm_icon.startsWith("/") ? realm_uri + realm_icon : realm_icon,
     url: realm_uri,
     alias: realm_name,
+    zulipVersion: zulip_version,
+    zulipFeatureLevel: zulip_feature_level,
   };
 };