fix(crawler): wrap wait_for_navigation in 30s timeout (0.36.1)

A hung TLS handshake or a page that never fires load could wedge a
worker (or the cron metadata pass) indefinitely — chromiumoxide
imposes no navigation timeout of its own.

New crawler::nav::wait_for_nav caps each navigation at NAV_TIMEOUT
(30s) and returns a typed NavError so timeouts surface as transient
(retryable) errors. Wired at the three navigation sites:
- source::target::navigate (catalog/detail/pagination)
- content::sync_chapter_content (chapter reader)
- session::fetch_probe_html (session probe)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/src/crawler/source/target.rs

@@ -21,6 +21,7 @@ use super::{
 use crate::crawler::detect::{
     has_logo_sentinel, is_broken_page_body, retry_on_transient, PageError,
 };
+use crate::crawler::nav::{wait_for_nav, NavError};
 
 /// `sources.id` value for this Source impl. Exposed as a const so the
 /// daemon can look up per-source state (e.g. the recovery flag) before
@@ -216,9 +217,17 @@ async fn navigate(ctx: &FetchContext<'_>, url: &str) -> Result<String, PageError
         .new_page(url)
         .await
         .map_err(|e| PageError::Other(anyhow::Error::from(e)))?;
-    page.wait_for_navigation()
-        .await
-        .map_err(|e| PageError::Other(anyhow::Error::from(e)))?;
+    match wait_for_nav(&page).await {
+        Ok(()) => {}
+        Err(NavError::Timeout(_)) => {
+            page.close().await.ok();
+            return Err(PageError::transient("nav timeout"));
+        }
+        Err(NavError::Cdp(e)) => {
+            page.close().await.ok();
+            return Err(PageError::Other(anyhow::Error::from(e)));
+        }
+    }
     // Stopgap until we wait on a specific selector per page type —
     // gives any post-load JS a beat to finish injecting content.
     tokio::time::sleep(Duration::from_secs(1)).await;