fix(crawler): harden crash & shutdown job recovery

Three failure-mode fixes surfaced by a crawler recovery audit:

- Graceful shutdown mid-dispatch now releases the in-flight job back to
  pending without burning a retry attempt. process_lease wraps the
  dispatch in a biased tokio::select! cancel arm that aborts the
  heartbeat and calls jobs::release; previously a mid-job SIGTERM left
  the row 'running' until lease expiry and cost one of max_attempts.

- Boot-time jobs::reclaim_orphaned resets 'running' jobs with an expired
  lease back to pending (attempt refunded), run once at daemon startup
  before workers start. Crash recovery is now immediate instead of
  waiting a full lease window for the lazy lease-expiry path. Safe under
  multi-replica: only already-expired leases are touched, which a
  healthy heartbeating peer never has.

- Manga-list parsing now warns when listing anchors are dropped for a
  missing/empty href or title (split into parse_manga_list_anchors so
  the drop count is testable), turning silent source markup drift into
  an observable signal. Returned refs are byte-identical to before.

Tests added: shutdown_mid_dispatch_releases_lease_without_burning_attempt,
reclaim_orphaned_resets_only_expired_running_jobs, and a drop-count unit
test. Patch bump 0.81.0 -> 0.81.1 (both manifests).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/src/app.rs

@@ -645,6 +645,17 @@ async fn spawn_crawler_daemon(
         })
     };
 
+    // Reclaim jobs orphaned by a previous crash/kill (running with an
+    // expired lease) before workers start, so recovery is immediate instead
+    // of waiting a full lease window for `lease`'s expiry clause. Safe under
+    // multi-replica: only already-expired leases are touched. Best-effort —
+    // a failure here just defers recovery to the lazy lease path.
+    match crate::crawler::jobs::reclaim_orphaned(&db).await {
+        Ok(0) => {}
+        Ok(n) => tracing::info!(reclaimed = n, "crawler: reclaimed orphaned in-flight jobs at startup"),
+        Err(e) => tracing::warn!(?e, "crawler: reclaim_orphaned at startup failed"),
+    }
+
     let daemon_handle = daemon::spawn(
         db,
         cancel,