feat(FN-5189): complete Step 3 — migrate supervised spawns

Fusion-Task-Id: FN-5189
Fusion-Task-Lineage: 4caa3f0a-af81-4c60-88e8-de229ed72e08

packages/cli/src/commands/dashboard-tui/app.tsx

@@ -33,6 +33,7 @@ function openInBrowser(url: string): void {
     args = [url];
   }
   try {
+    // process-supervisor-allowlist: user-facing browser opener must outlive the TUI process
     const child = spawn(cmd, args, { detached: true, stdio: "ignore" });
     child.unref();
   } catch {