feat(llm-inference): move astro-orbiter monitoring to GitOps (values.yaml + dashboards.yaml)

- Prometheus scrape configs for node/gpu/llama-server exporters on
  astro-orbiter now declared in cluster/applications/monitoring/values.yaml
  (additionalScrapeConfigs), applied via ArgoCD sync instead of an
  imperative kubectl secret patch from the Ansible role.
- Grafana dashboard for astro-orbiter LLM inference added as a ConfigMap
  in cluster/applications/monitoring/dashboards.yaml (grafana_dashboard=1
  sidecar label), replacing the role's ad-hoc kubectl apply of a rendered
  Jinja template.
- ansible/roles/llm-inference/tasks/monitoring.yml: removed the kubectl
  get/patch/apply tasks and orphaned grafana-llm-dashboard.json.j2
  template; role now only stands up node_exporter + nvidia_gpu_exporter
  and verifies they're reachable — cluster-facing config lives in Git.
- host_vars/vars.yml + inventory.yml: finalize astro-orbiter as the
  llama.cpp/RTX 3090 host (jarvis user, ssh key), drop stale Ollama/AMD
  vars and ollama_server inventory group superseded by the ATX rebuild.

ansible/host_vars/astro-orbiter/vars.yml

@@ -2,11 +2,14 @@
 # ------------------------------------------------------------------------------
 # FILE: ansible/host_vars/astro_orbiter/vars.yml
 # HOST: astro-orbiter (10.1.71.130)
-# ROLE: Ollama inference host with AMD RX 5700 GPU passthrough
+# ROLE: llama.cpp LLM inference host — Ryzen 7 5800XT / RTX 3090 (ATX rebuild,
+#       2026-08-04). Superseded the prior AMD RX 5700 / Ollama config below;
+#       drive was transplanted into new hardware, not reinstalled.
 # ------------------------------------------------------------------------------
 
 ansible_host: 10.1.71.130
-ansible_user: wed
+ansible_user: jarvis
+ansible_ssh_private_key_file: ~/.ssh/id_jarvis
 ansible_become: true
 
 # LVM root expansion — xlarge template uses sda3 partition, standard VG/LV names
@@ -15,11 +18,3 @@ common_root_pv: /dev/sda3
 common_root_vg: ubuntu-vg
 common_root_lv: ubuntu-lv
 
-# Ollama — all defaults apply; explicitly documented here for visibility
-ollama_rocm_version: "6.2"
-ollama_default_model: "qwen3:8b"
-ollama_hsa_override_gfx_version: "10.1.0"
-ollama_data_disk: /dev/sdb
-ollama_data_vg: ollama-vg
-ollama_data_lv: ollama-lv
-ollama_data_dir: /var/lib/ollama