Switch to ES module exports for wws runtime

- Replace module.exports with export default
- wws uses ES modules, not CommonJS
- Fixes 'module is not defined' error

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

chat/index.js

@@ -22,8 +22,10 @@ async function handler(request) {
 
   try {
     const body = await request.json()
-    const { message, project_id, user_id, provider } = body
-    const selectedProvider = provider || 'zai'
+    const message = body.message
+    const project_id = body.project_id
+    const user_id = body.user_id
+    const provider = body.provider || 'zai'
 
     if (!message) {
       return new Response(JSON.stringify({ error: 'Message is required' }), {
@@ -40,7 +42,7 @@ async function handler(request) {
         message: message,
         project_id: project_id || null,
         user_id: user_id || null,
-        provider: selectedProvider,
+        provider: provider,
         source: 'wws-proxy',
         timestamp: new Date().toISOString()
       })
@@ -51,7 +53,7 @@ async function handler(request) {
     return new Response(JSON.stringify({
       success: true,
       response: result.response || result,
-      provider: selectedProvider,
+      provider: provider,
       timestamp: new Date().toISOString()
     }), {
       headers: corsHeaders
@@ -68,4 +70,5 @@ async function handler(request) {
   }
 }
 
-module.exports = { handler }
+// ES Module export for wws
+export default handler