fix(infra): make browser relay bind address configurable

Add browser.relayBindHost config option so the Chrome extension relay
server can bind to a non-loopback address (e.g. 0.0.0.0 for WSL2).
Defaults to 127.0.0.1 when unset, preserving current behavior.

Closes #39214

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

src/browser/server-lifecycle.ts

@@ -16,7 +16,10 @@ export async function ensureExtensionRelayForProfiles(params: {
     if (!profile || profile.driver !== "extension") {
       continue;
     }
-    await ensureChromeExtensionRelayServer({ cdpUrl: profile.cdpUrl }).catch((err) => {
+    await ensureChromeExtensionRelayServer({
+      cdpUrl: profile.cdpUrl,
+      bindHost: params.resolved.relayBindHost,
+    }).catch((err) => {
       params.onWarn(`Chrome extension relay init failed for profile "${name}": ${String(err)}`);
     });
   }