Initial commit: arr-stack homelab + local AI

Docker Compose media stack (gluetun, *arr, Jellyfin), Ternary-Bonsai AI
(Open WebUI, Forgejo, optional OpenHands), and Ansible bootstrap for the
SER5 Ubuntu host.

ansible/roles/docker/tasks/main.yml

@@ -0,0 +1,91 @@
+---
+- name: Install Docker apt prerequisites
+  ansible.builtin.apt:
+    name:
+      - ca-certificates
+      - curl
+      - gnupg
+    state: present
+  tags: [docker]
+
+- name: Create keyrings directory
+  ansible.builtin.file:
+    path: /etc/apt/keyrings
+    state: directory
+    mode: "0755"
+  tags: [docker]
+
+- name: Add Docker official GPG key
+  ansible.builtin.get_url:
+    url: https://download.docker.com/linux/ubuntu/gpg
+    dest: /etc/apt/keyrings/docker.asc
+    mode: "0644"
+    force: true
+  tags: [docker]
+
+- name: Add Docker apt repository (deb822)
+  ansible.builtin.deb822_repository:
+    name: docker
+    types: [deb]
+    uris: https://download.docker.com/linux/ubuntu
+    suites: ["{{ ansible_distribution_release }}"]
+    components: [stable]
+    architectures: "{{ [ansible_architecture | replace('x86_64', 'amd64') | replace('aarch64', 'arm64')] }}"
+    signed_by: /etc/apt/keyrings/docker.asc
+    state: present
+    enabled: true
+  tags: [docker]
+
+- name: Install Docker Engine + Compose plugin
+  ansible.builtin.apt:
+    name: "{{ docker_packages }}"
+    state: present
+    update_cache: true
+  tags: [docker]
+
+- name: Ensure docker group exists
+  ansible.builtin.group:
+    name: docker
+    state: present
+  tags: [docker]
+
+- name: Configure Docker daemon.json
+  ansible.builtin.copy:
+    dest: /etc/docker/daemon.json
+    mode: "0644"
+    content: "{{ docker_daemon_json | to_nice_json }}\n"
+  notify: Restart docker
+  tags: [docker]
+
+- name: Enable and start Docker (survives reboots)
+  ansible.builtin.systemd:
+    name: docker
+    state: started
+    enabled: true
+  tags: [docker]
+
+- name: Enable containerd (Docker dependency)
+  ansible.builtin.systemd:
+    name: containerd
+    state: started
+    enabled: true
+  tags: [docker]
+
+- name: Add stack user to docker / video / render groups
+  ansible.builtin.user:
+    name: "{{ stack_owner }}"
+    groups: "{{ extra_user_groups }}"
+    append: true
+  tags: [docker, users]
+  # Full permission setup also runs in the users role
+
+- name: Verify docker works
+  ansible.builtin.command: docker version --format '{% raw %}{{.Server.Version}}{% endraw %}'
+  register: docker_ver
+  changed_when: false
+  tags: [docker]
+
+- name: Show docker version
+  ansible.builtin.debug:
+    msg: "Docker server {{ docker_ver.stdout }}"
+  tags: [docker]