fix(server): gestion erreur WebSocket au build + rewrite URL protocol-relative dans le proxy

- api/websocket: capture asynchrone EADDRINUSE pour ne pas bloquer le build
- proxy: réécrit aussi les URLs protocol-relatives (//localhost) dans le corps

server/app/api/proxy/[[...path]]/route.ts

@@ -111,7 +111,8 @@ async function proxyRequest(req: NextRequest) {
     });
   }
 
-  // For text responses, rewrite localhost/internal URLs to the public URL
+  // For text responses, rewrite localhost/internal URLs to the public URL.
+  // Also handle protocol-relative URLs that some WordPress plugins/themes use.
   let body = await upstreamRes.text();
   const localBase = `http://${instance.node.tailscaleIp}:${instance.port}`;
   const localBaseHttps = `https://${instance.node.tailscaleIp}:${instance.port}`;
@@ -119,6 +120,8 @@ async function proxyRequest(req: NextRequest) {
   const localLocalhostHttps = `https://localhost:${instance.port}`;
   const localLocalhostPlainHttp = `http://localhost`;
   const localLocalhostPlainHttps = `https://localhost`;
+  const localLocalhostProtocolRelative = `//localhost`;
+  const localTailscaleProtocolRelative = `//${instance.node.tailscaleIp}:${instance.port}`;
 
   body = body
     .replaceAll(localBase, publicUrl)
@@ -126,7 +129,9 @@ async function proxyRequest(req: NextRequest) {
     .replaceAll(localLocalhostHttp, publicUrl)
     .replaceAll(localLocalhostHttps, publicUrl)
     .replaceAll(localLocalhostPlainHttp, publicUrl)
-    .replaceAll(localLocalhostPlainHttps, publicUrl);
+    .replaceAll(localLocalhostPlainHttps, publicUrl)
+    .replaceAll(localTailscaleProtocolRelative, publicUrl.replace(/^https?:/, ""))
+    .replaceAll(localLocalhostProtocolRelative, publicUrl.replace(/^https?:/, ""));
 
   return new Response(body, {
     status: upstreamRes.status,