reintroduce shadowing metrics

Author: paulohtb6

modules/manage/pages/disaster-recovery/shadowing/monitor.adoc

@@ -56,6 +56,10 @@ Shadowing provides comprehensive metrics to track replication performance and he
 |===
 |Metric |Type |Description
 
+|xref:reference:public-metrics-reference.adoc#redpanda_shadow_link_client_errors[`redpanda_shadow_link_client_errors`]
+|Counter
+|Total number of errors encountered by the Kafka client during shadow link operations. Monitor by `shadow_link_name` to identify connection issues, authentication failures, or other client-side problems.
+
 |xref:reference:public-metrics-reference.adoc#redpanda_shadow_link_shadow_lag[`redpanda_shadow_link_shadow_lag`]
 |Gauge
 |The lag of the shadow partition against the source partition, calculated as source partition LSO (Last Stable Offset) minus shadow partition HWM (High Watermark). Monitor by `shadow_link_name`, `topic`, and `partition` to understand replication lag for each partition.

modules/reference/pages/public-metrics-reference.adoc

@@ -2374,6 +2374,18 @@ Number of shadow topics in the respective states. Monitor this metric to track t
 
 ---
 
+=== redpanda_shadow_link_client_errors
+
+Total number of errors encountered by the Kafka client during shadow link operations. Monitor this metric to identify connection issues, authentication failures, or other client-side problems affecting shadow link replication.
+
+*Type*: counter
+
+*Labels*:
+
+- `shadow_link_name` - Name of the shadow link
+
+---
+
 === redpanda_shadow_link_total_bytes_fetched
 
 Total number of bytes fetched by a sharded replicator (bytes received by the client). Use this metric to track data transfer volume from the source cluster.