feat(semaphore): install Ansible collections via bind-mounted host directory

- New tasks/collections.yml installs collections from defaults list
  into /opt/semaphore/ansible-collections on the host
- semaphore.container.j2: bind-mounts that dir into the container at
  /home/semaphore/.ansible/collections (read-only)
- defaults/main.yml: semaphore_collections_dir + semaphore_ansible_collections
  list (containers.podman, effectivelywild.technitium_dns)
- main.yml: collections task wired in after semaphore.yml, before verify
- Collections survive container restarts/rebuilds without image changes
- Re-run with --tags collections to add new collections without full redeploy

ansible/roles/semaphore/tasks/main.yml

@@ -31,6 +31,10 @@
   ansible.builtin.import_tasks: semaphore.yml
   tags: [semaphore]
 
+- name: Install Ansible collections for Semaphore
+  ansible.builtin.import_tasks: collections.yml
+  tags: [semaphore, collections]
+
 - name: Verify Semaphore is reachable
   ansible.builtin.import_tasks: verify.yml
   tags: [semaphore, verify]