fix: default to 0.0.0.0 to fix WSL2 health check failure (#520)

PR #470 changed the default listen host to undefined, letting Node.js
bind to IPv6 :: on systems that support it. This broke WSL2 where IPv6
dual-stack is unreliable — the server binds to :: but IPv4 127.0.0.1
connections fail, causing the health check to time out.

Revert to 0.0.0.0 as the default. Users who need IPv6 can set
BIND_HOST=:: explicitly.

Fixes #518

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

packages/server/src/services/shutdown.ts

@@ -8,6 +8,9 @@ export function bindShutdown(server: any, groupChatServer?: any, chatRunServer?:
     if (isShuttingDown) return
     isShuttingDown = true
 
+    // Force exit after 3s no matter what
+    setTimeout(() => process.exit(0), 3000)
+
     logger.info('Shutting down (%s)...', signal)
 
     try {
@@ -24,13 +27,16 @@ export function bindShutdown(server: any, groupChatServer?: any, chatRunServer?:
         logger.info('Socket.IO closed')
       }
 
-      if (server) {
-        await new Promise<void>((resolve) => {
-          server.close(() => {
-            logger.info('HTTP server closed')
-            resolve()
+      const servers = Array.isArray(server) ? server : [server].filter(Boolean)
+      if (servers.length) {
+        await Promise.all(servers.map((httpServer) => (
+          new Promise<void>((resolve) => {
+            httpServer.close(() => {
+              logger.info('HTTP server closed')
+              resolve()
+            })
           })
-        })
+        )))
       }
     } catch (err) {
       logger.error(err, 'Shutdown error')