Update deployment pipeline, Makefile and README

- Makefile: add install_dev, install_prod, migrations, clear_prod, maintenance commands
- Playbook: full deploy flow (maintenance, stop, install, start, migrate, clear, caddy, messenger)
- Supervisor config for 2 messenger instances
- Workflow: SSH key setup with server IP
- hosts.ini: use IP instead of domain, sudo without password
- README: full documentation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/deploy.yml

@@ -13,5 +13,12 @@ jobs:
       - name: Install Ansible
         run: apt-get update && apt-get install -y ansible
 
-      - name: Deploy Caddy config
+      - name: Setup SSH key
+        run: |
+          mkdir -p ~/.ssh
+          echo "${{ secrets.SSH_PRIVATE_KEY }}" > ~/.ssh/id_ed25519
+          chmod 600 ~/.ssh/id_ed25519
+          ssh-keyscan 34.90.187.4 >> ~/.ssh/known_hosts
+
+      - name: Deploy
         run: ansible-playbook -i ansible/hosts.ini ansible/deploy-caddy.yml --vault-password-file <(echo "${{ secrets.ANSIBLE_VAULT_PASSWORD }}")