Update ISO installer tiers and backend deployment

ansible/roles/cezen-backend/tasks/main.yml

@@ -0,0 +1,113 @@
+---
+# cezen-backend role: installs the Nexus One AI FastAPI management API
+
+- name: Install system Python deps
+  apt:
+    name:
+      - python3-pip
+      - python3-venv
+      - python3.11
+      - python3.11-venv
+      - libmupdf-dev      # required by pymupdf (Document Intelligence)
+      - mupdf-tools
+    state: present
+    update_cache: yes
+
+- name: Create backend directory
+  file:
+    path: /opt/cezen/backend
+    state: directory
+    owner: "{{ cezen_user }}"
+    group: "{{ cezen_user }}"
+    mode: "0755"
+
+- name: Create data directory (JWT secret + SQLite DB)
+  file:
+    path: /opt/cezen/data
+    state: directory
+    owner: "{{ cezen_user }}"
+    group: "{{ cezen_user }}"
+    mode: "0750"
+
+- name: Copy FastAPI application
+  copy:
+    src: main.py
+    dest: /opt/cezen/backend/main.py
+    owner: "{{ cezen_user }}"
+    group: "{{ cezen_user }}"
+    mode: "0644"
+  notify: Restart cezen-api
+
+- name: Copy QLoRA training runner
+  copy:
+    src: train_qlora.py
+    dest: /opt/cezen/backend/train_qlora.py
+    owner: "{{ cezen_user }}"
+    group: "{{ cezen_user }}"
+    mode: "0755"
+
+- name: Copy requirements.txt
+  copy:
+    src: requirements.txt
+    dest: /opt/cezen/backend/requirements.txt
+    owner: "{{ cezen_user }}"
+    group: "{{ cezen_user }}"
+    mode: "0644"
+
+- name: Create Python virtual environment (Python 3.11)
+  become_user: "{{ cezen_user }}"
+  command: python3.11 -m venv /opt/cezen/backend/venv
+  args:
+    creates: /opt/cezen/backend/venv/bin/activate
+
+- name: Install Python dependencies
+  become_user: "{{ cezen_user }}"
+  pip:
+    requirements: /opt/cezen/backend/requirements.txt
+    virtualenv: /opt/cezen/backend/venv
+  notify: Restart cezen-api
+
+- name: Install Pro/Max fine-tuning dependencies
+  become_user: "{{ cezen_user }}"
+  pip:
+    name:
+      - torch
+      - transformers
+      - datasets
+      - peft
+      - bitsandbytes
+      - accelerate
+      - trl
+      - sentencepiece
+    virtualenv: /opt/cezen/backend/venv
+  retries: 3
+  delay: 15
+  when: (tier | default('basic')) in ['pro', 'max']
+
+- name: Install Max multi-GPU training dependencies
+  become_user: "{{ cezen_user }}"
+  pip:
+    name:
+      - deepspeed
+    virtualenv: /opt/cezen/backend/venv
+  retries: 3
+  delay: 15
+  when: (tier | default('basic')) == 'max'
+
+- name: Install systemd service unit
+  copy:
+    src: cezen-api.service
+    dest: /etc/systemd/system/cezen-api.service
+    owner: root
+    group: root
+    mode: "0644"
+  notify:
+    - Reload systemd
+    - Restart cezen-api
+
+- name: Enable and start cezen-api service
+  systemd:
+    name: cezen-api
+    enabled: yes
+    state: started
+    daemon_reload: yes