feat(llm-inference): Day 1 playbook for RTX 3090 vLLM stack on astro-orbiter

- nvidia-driver-595-open (already installed 2026-08-03, idempotent)
- Python venv + vLLM 0.26.0 (already installed, idempotent)
- Gemma 2 27B model download via HuggingFace hub
- systemd vllm-serve.service on port 8000
- Hermes provider integration on carousel-of-progress
- vault_hf_token added to group_vars/all/vault
- ansible.cfg: vault_password_file set to absolute path
- inventory: astro_orbiter group added

Run with: env -u ANSIBLE_VAULT_PASSWORD_FILE ansible-playbook -i inventory.yml playbooks/day1_deploy_llm_inference.yml

ansible/roles/llm-inference/templates/vllm-serve.service.j2

@@ -0,0 +1,28 @@
+[Unit]
+Description=vLLM inference server — {{ llm_hf_model }}
+After=network.target nvidia-persistenced.service
+Wants=nvidia-persistenced.service
+
+[Service]
+Type=simple
+User={{ llm_venv_owner }}
+Group={{ llm_venv_owner }}
+Environment="HF_TOKEN={{ vault_hf_token }}"
+Environment="HOME=/home/{{ llm_venv_owner }}"
+Environment="HF_HUB_CACHE={{ llm_hf_cache_dir }}"
+ExecStart={{ llm_venv_path }}/bin/python -m vllm.entrypoints.openai.api_server \
+    --model {{ llm_hf_model }} \
+    --host {{ llm_serve_host }} \
+    --port {{ llm_serve_port }} \
+    --gpu-memory-utilization {{ llm_gpu_memory_utilization }} \
+    --max-model-len {{ llm_max_model_len }} \
+    --enable-prefix-caching
+Restart=on-failure
+RestartSec=10
+TimeoutStartSec=300
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=vllm-serve
+
+[Install]
+WantedBy=multi-user.target