Add Kavita as the new book server

Runs next to Calibre-Web at a temporary kavita. subdomain until it takes
over books. Each book lives in its own folder under
/opt/stacks/kavita/books, because Kavita names a book after its folder.
The admin password is in the vault as vault_kavita.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

roles/docker/templates/kavita-compose.yml.j2

@@ -0,0 +1,25 @@
+---
+services:
+  kavita:
+    image: jvmilazz0/kavita:latest
+    container_name: kavita
+    environment:
+      - TZ=America/Denver
+    volumes:
+      - ./config:/kavita/config
+      # Kavita names a book after its folder, so each book goes in its own folder:
+      #   scp -r "Book Title/" docker-01:/opt/stacks/kavita/books/
+      - ./books:/books
+    extra_hosts:
+      - "{{ subdomains.pocketid }}:{{ docker.hairpin_ip }}"
+    restart: unless-stopped
+    labels:
+      glance.name: Kavita
+      glance.icon: si:book
+      glance.url: https://{{ subdomains.kavita }}/
+      glance.description: Book server
+      mag37.dockcheck.update: true
+networks:
+  default:
+    external: true
+    name: {{ docker.network_name }}