fix: inject pod_name, namespace, node_name into JSON log output

Reads from RuntimeContext (detected once at startup). On K8s, these
fields appear in every JSON log line for correlation. On bare metal,
fields are None and injection is skipped (no overhead).

Uses the existing inject_and_redact_json_line mechanism alongside
service_name and service_version.

Author: catinspace-au

src/logger/masking.rs

@@ -256,6 +256,27 @@ fn inject_and_redact_json_line(
                     serde_json::Value::String(ver.to_string()),
                 );
             }
+
+            // Inject K8s context fields (no-op on bare metal — fields are None)
+            let ctx = crate::env::runtime_context();
+            if let Some(ref pod) = ctx.pod_name {
+                map.insert(
+                    "pod_name".to_string(),
+                    serde_json::Value::String(pod.clone()),
+                );
+            }
+            if let Some(ref ns) = ctx.namespace {
+                map.insert(
+                    "namespace".to_string(),
+                    serde_json::Value::String(ns.clone()),
+                );
+            }
+            if let Some(ref node) = ctx.node_name {
+                map.insert(
+                    "node_name".to_string(),
+                    serde_json::Value::String(node.clone()),
+                );
+            }
         }
         redact_json_value(&mut value, sensitive);
         let mut result = serde_json::to_string(&value).unwrap_or_else(|_| trimmed.to_string());