Add logfmt parser for k8s log level extraction

The JSON parser only works for JSON-formatted logs. Many Go services
(Loki, Prometheus, etc.) use logfmt format. Add logfmt parser to extract
level, caller, and component labels for better log filtering in Grafana.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

argocd/manifests/alloy-k8s/configmap.yaml

@@ -89,7 +89,7 @@ data:
         expression = "v1 Endpoints is deprecated"
       }
 
-      // Try to parse JSON logs
+      // Try to parse JSON logs (e.g., structured app logs)
       stage.json {
         expressions = {
           level   = "level",
@@ -98,10 +98,22 @@ data:
         }
       }
 
-      // Extract level from parsed JSON if available
+      // Try to parse logfmt logs (e.g., Loki, Prometheus, Go services)
+      stage.logfmt {
+        mapping = {
+          level     = "level",
+          ts        = "ts",
+          caller    = "caller",
+          component = "component",
+        }
+      }
+
+      // Extract labels from parsed data (works for both JSON and logfmt)
       stage.labels {
         values = {
-          level = "",
+          level     = "",
+          caller    = "",
+          component = "",
         }
       }
     }