feat(ansible): standardize Neo4j ports and add monitoring

- Unify Neo4j HTTP/Bolt/syslog ports across ariel and umbriel hosts
- Add neo4j_metrics_port (22094) for APOC exporter sidecar
- Add umbriel to Prometheus node_exporter targets
- Add Neo4j scrape config and alerts for tx rollback rate and
  stalled store growth
- Replace kernos_harper MCP with andromeda (caliban.helu.ca)
- Remove angelia MCP from kottos fastagent config
- Switch neo4j group membership from keeper_user to ponos

ansible/neo4j/deploy.yml

@@ -24,9 +24,9 @@
       group: "{{neo4j_group}}"
       system: true
 
-  - name: Add group neo4j to keeper_user
+  - name: Add group neo4j to user ponos
     ansible.builtin.user:
-      name: "{{keeper_user}}"
+      name: ponos
       groups: "{{neo4j_group}}"
       append: true
 
@@ -38,6 +38,14 @@
       state: directory
       mode: '750'
 
+  - name: Create neo4j data directory
+    ansible.builtin.file:
+      path: "{{neo4j_directory}}/data"
+      owner: "{{neo4j_user}}"
+      group: "{{neo4j_group}}"
+      state: directory
+      mode: '750'
+
   - name: Template docker-compose file
     ansible.builtin.template:
       src: docker-compose.yml.j2