fix sre rewrite slice offset: /api/sre is 8 chars, not 9 (#1359)

server.js

@@ -91,7 +91,7 @@ app.use('/api', requireApiBearer);
 // Rewrite /api/sre/* → /api/* so the gateway can forward channel-prefixed paths.
 app.use((req, res, next) => {
     if (req.url.startsWith('/api/sre')) {
-        req.url = '/api' + req.url.slice(9);
+        req.url = '/api' + req.url.slice(8);
     }
     next();
 });