refactor: rename k8s-manifests directory to manifests

- Rename all `k8s-manifests` subdirectories and files to `manifests`
- Update all file paths in `argocd-init.yml` to reflect the new directory name

🤖

manifests/monitoring/zabbix-proxy.jsonnet

@@ -0,0 +1,21 @@
+local app = import "../../_templates/argocd_app.libsonnet";
+
+[
+app + {
+  name:: "zabbix-proxy",
+  namespace:: "monitoring",
+  chart:: "zabbix-helm-chrt",
+  repo:: "https://cdn.zabbix.com/zabbix/integrations/kubernetes-helm/6.4",
+  version:: "1.3.*",
+  values:: |||
+    zabbixAgent:
+      enabled: false
+    zabbixProxy:
+      env:
+        - name: ZBX_HOSTNAME
+          value: zabbix-proxy
+        - name: ZBX_SERVER_HOST
+          value: "zabbix.smsvc.net"
+  |||
+}
+]