docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

ansible/loki/deploy.yml

@@ -0,0 +1,89 @@
+---
+- name: Deploy Loki to Prospero
+  hosts: ubuntu
+  become: true
+  tasks:
+  - name: Check if host has loki service
+    ansible.builtin.set_fact:
+      has_loki_service: "{{'loki' in services}}"
+
+  - name: Skip hosts without loki service
+    ansible.builtin.meta: end_host
+    when: not has_loki_service
+
+  - name: Add Grafana repository
+    ansible.builtin.deb822_repository:
+      name: grafana
+      types: [deb]
+      uris: https://apt.grafana.com
+      suites: [stable]
+      components: [main]
+      signed_by: https://apt.grafana.com/gpg.key
+      state: present
+
+  - name: Install Loki
+    become: true
+    ansible.builtin.apt:
+      name:
+        - loki
+      state: present
+      update_cache: true
+
+  - name: Create loki group
+    become: true
+    ansible.builtin.group:
+      name: "{{loki_group}}"
+
+  - name: Create loki user
+    become: true
+    ansible.builtin.user:
+      name: "{{loki_user}}"
+      comment: "{{loki_user}}"
+      group: "{{loki_group}}"
+      system: true
+
+  - name: Add group loki to ansible_user
+    become: true
+    ansible.builtin.user:
+      name: "{{ansible_user}}"
+      groups: "{{loki_group}}"
+      append: true
+
+  - name: Create loki directories
+    become: true
+    ansible.builtin.file:
+      path: "{{item}}"
+      owner: "{{loki_user}}"
+      group: "{{loki_group}}"
+      state: directory
+      mode: '750'
+    loop:
+      - "{{loki_data_dir}}"
+      - "{{loki_config_dir}}"
+
+  - name: Template Loki configuration
+    become: true
+    ansible.builtin.template:
+      src: "{{loki_config_file}}.j2"
+      dest: "{{loki_config_dir}}/{{loki_config_file}}"
+      owner: "{{loki_user}}"
+      group: "{{loki_group}}"
+      mode: '550'
+    notify: restart loki
+
+  - name: Reset SSH connection to apply group changes
+    meta: reset_connection
+
+  - name: Enable and start Loki service
+    become: true
+    ansible.builtin.systemd:
+      name: loki
+      enabled: true
+      state: started
+
+  handlers:
+  - name: restart loki
+    become: true
+    ansible.builtin.systemd:
+      name: loki
+      state: restarted