fix: strip AIUI-specific fields from Claude API proxy requests

Remove webSearch, webResults, context fields before forwarding to
Anthropic API — these are AIUI-internal and cause 400 errors.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

neode-ui/mock-backend.js

@@ -1031,10 +1031,14 @@ app.post('/aiui/api/claude/*', (req, res) => {
 
   const apiPath = '/' + req.params[0]
 
-  // Ensure max_tokens is set — Claude API requires it but AIUI may omit it
+  // Clean request body for Anthropic API
   const body = req.body
-  if (body && !body.max_tokens) {
-    body.max_tokens = 4096
+  if (body) {
+    if (!body.max_tokens) body.max_tokens = 4096
+    // Strip AIUI-specific fields that Anthropic API rejects
+    delete body.webSearch
+    delete body.webResults
+    delete body.context
   }
 
   const bodyStr = JSON.stringify(body)