Add shared Kubernetes configuration files

- Add k8s/configmap.yaml with shared environment variables
- Add k8s/lpt-secrets.yaml template (secrets not committed)
- Add k8s/regcred-secret.yaml template (managed by workflow)
- Add k8s/README.md with deployment instructions
- Remove incorrect deployment/service files from root k8s/

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

k8s/regcred-secret.yaml

@@ -0,0 +1,26 @@
+# Docker Registry Secret for pulling images from private registry
+#
+# This file is a TEMPLATE - the actual secret is managed by Gitea Actions workflow
+# and should NOT be committed with real credentials.
+#
+# To create this secret manually:
+# kubectl create secret docker-registry regcred \
+#   --docker-server=192.168.123.199:5000 \
+#   --docker-username=admin \
+#   --docker-password=<REGISTRY_PASSWORD> \
+#   --namespace=lpt-dev
+#
+# Or use the workflow which reads from Gitea secrets:
+# - REGISTRY_USERNAME
+# - REGISTRY_PASSWORD
+
+apiVersion: v1
+kind: Secret
+metadata:
+  name: regcred
+  namespace: lpt-dev
+type: kubernetes.io/dockerconfigjson
+data:
+  # .dockerconfigjson: <base64-encoded-docker-config>
+  # This is generated by the workflow - DO NOT commit real values here
+  .dockerconfigjson: ""