fix: load balancer panics, stealth flag, shadow DOM polyfill

Fixes #1: replace unwrap() panics in run_multi_worker_serve with match on the Result.
Fixes #2: route /json round-robin via worker_port instead of hardcoded port+1.
Fixes #3: return 502 Bad Gateway when a worker is unreachable instead of silently dropping the connection.
Fixes #5: thread --stealth through start_with_options -> CdpContext -> BrowserContext::with_options so the flag actually has an effect in serve mode (was let _ before). Log message now reflects the actual capability based on the stealth cargo feature being compiled in.
Fixes #15: try/catch the parentNode assignment in the attachShadow polyfill so it doesn't throw a TypeError against the read-only Node.parentNode getter (Cloudflare Turnstile triggers this path).

crates/obscura-cdp/src/server.rs

@@ -24,10 +24,14 @@ enum ServerMessage {
 }
 
 pub async fn start(port: u16) -> anyhow::Result<()> {
-    start_with_options(port, None).await
+    start_with_options(port, None, false).await
 }
 
-pub async fn start_with_options(port: u16, proxy: Option<String>) -> anyhow::Result<()> {
+pub async fn start_with_options(
+    port: u16,
+    proxy: Option<String>,
+    stealth: bool,
+) -> anyhow::Result<()> {
     let addr = SocketAddr::from(([127, 0, 0, 1], port));
     let listener = TcpListener::bind(&addr).await?;
 
@@ -42,7 +46,7 @@ pub async fn start_with_options(port: u16, proxy: Option<String>) -> anyhow::Res
         .run_until(async {
             let (msg_tx, msg_rx) = mpsc::unbounded_channel::<ServerMessage>();
 
-            let processor_handle = tokio::task::spawn_local(cdp_processor(msg_rx, proxy));
+            let processor_handle = tokio::task::spawn_local(cdp_processor(msg_rx, proxy, stealth));
 
             loop {
                 match listener.accept().await {
@@ -67,8 +71,9 @@ pub async fn start_with_options(port: u16, proxy: Option<String>) -> anyhow::Res
 async fn cdp_processor(
     mut rx: mpsc::UnboundedReceiver<ServerMessage>,
     proxy: Option<String>,
+    stealth: bool,
 ) {
-    let mut ctx = CdpContext::new_with_proxy(proxy);
+    let mut ctx = CdpContext::new_with_options(proxy, stealth);
     let (itx, irx) = mpsc::unbounded_channel::<obscura_js::ops::InterceptedRequest>();
     ctx.intercept_tx = Some(itx);
     let mut intercept_rx: Option<mpsc::UnboundedReceiver<obscura_js::ops::InterceptedRequest>> = Some(irx);
@@ -632,4 +637,4 @@ async fn handle_http_json(stream: TcpStream, port: u16, endpoint: &str) -> anyho
     stream.write_all(resp.as_bytes()).await?;
     stream.flush().await?;
     Ok(())
-}
+}