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/tasks/vllm.yml

@@ -0,0 +1,41 @@
+---
+# ------------------------------------------------------------------------------
+# FILE: roles/llm-inference/tasks/vllm.yml
+# DESCRIPTION: Phase 3 — Python venv + vLLM install.
+#              Idempotent: venv creation and pip install only run if the
+#              venv binary or vllm package is absent.
+#              Already completed manually on 2026-08-03 — will no-op.
+# ------------------------------------------------------------------------------
+
+- name: Create Python venv for vLLM
+  ansible.builtin.command:
+    cmd: python3 -m venv {{ llm_venv_path }}
+    creates: "{{ llm_venv_path }}/bin/python"
+  become: true
+  become_user: "{{ llm_venv_owner }}"
+
+- name: Upgrade pip inside venv
+  ansible.builtin.pip:
+    name: pip
+    state: latest
+    virtualenv: "{{ llm_venv_path }}"
+  become: true
+  become_user: "{{ llm_venv_owner }}"
+
+- name: Install vLLM
+  ansible.builtin.pip:
+    name: vllm
+    state: present
+    virtualenv: "{{ llm_venv_path }}"
+  become: true
+  become_user: "{{ llm_venv_owner }}"
+
+- name: Verify vLLM is importable
+  ansible.builtin.command:
+    cmd: "{{ llm_venv_path }}/bin/python -c 'import vllm; print(vllm.__version__)'"
+  register: vllm_version
+  changed_when: false
+
+- name: Print vLLM version
+  ansible.builtin.debug:
+    msg: "vLLM version: {{ vllm_version.stdout }}"