Treat omitted host_apps.enabled as true (#36)

Closes #35.

## Summary
- `#33` used Jinja `rejectattr('enabled', 'equalto', false)` to skip stopped apps. That filter **requires** the key, so every `host_apps` row that omits `enabled` (the documented default) crashed deploy on all webservers before git/compose.
- Filter with `item.enabled | default(true)` instead, in `app-deploy` and `web-static`. `print_forge` (`enabled: false`) still skipped. `url_shortening_service` and every other omitted-key row deploy again.

## Test plan
- [ ] `ansible-playbook playbooks/deploy-apps.yml --syntax-check`
- [ ] Redeploy `url_shortening_service` beta: `deploy.sh --app url_shortening_service --env beta --ref <sha>`
- [ ] Confirm `print_forge` is still not started (no compose up on 8007/8019)

Reviewed-on: #36

roles/app-deploy/tasks/main.yml

@@ -35,14 +35,24 @@
     - app_env is defined
     - matching_host_apps | length == 0
 
+# rejectattr('enabled', …) raises when the key is omitted. Omit = enabled (#35).
+- name: Reset deploy targets
+  ansible.builtin.set_fact:
+    deploy_targets: []
+
 - name: "Drop disabled host_apps (enabled: false)"
   ansible.builtin.set_fact:
-    deploy_targets: "{{ matching_host_apps | rejectattr('enabled', 'equalto', false) | list }}"
+    deploy_targets: "{{ deploy_targets + [item] }}"
+  loop: "{{ matching_host_apps }}"
+  when: item.enabled | default(true)
+  loop_control:
+    label: "{{ item.name }}/{{ item.env }}"
 
 - name: Show skipped disabled apps
   ansible.builtin.debug:
     msg: "skip disabled {{ item.name }}/{{ item.env }} on {{ inventory_hostname }}"
-  loop: "{{ matching_host_apps | selectattr('enabled', 'equalto', false) | list }}"
+  loop: "{{ matching_host_apps }}"
+  when: not (item.enabled | default(true))
   loop_control:
     label: "{{ item.name }}/{{ item.env }}"