Refactor DNS handling and add solo record support

- Added 'solo' flag support for A/AAAA, CNAME/MX/TXT, and SRV records in sys-dns-cloudflare-records.
- Simplified sys-svc-dns: removed NS management tasks and CLOUDFLARE_NAMESERVERS default.
- Renamed 03_apex.yml back to 02_apex.yml, adjusted AAAA task name.
- Updated web-app-bluesky DNS tasks: marked critical records with 'solo'.
- Updated web-app-mailu DNS tasks: removed cleanup block, enforced 'solo' on all records.
- Adjusted constructor stage to call domain_mappings with AUTO_BUILD_ALIASES parameter.

Conversation: https://chatgpt.com/share/68cd20d8-9ba8-800f-b070-f7294f072c40

roles/sys-svc-dns/tasks/02_apex.yml

@@ -0,0 +1,28 @@
+---
+- name: "Ensure A @ for {{ base_domain }}"
+  community.general.cloudflare_dns:
+    api_token:  "{{ CLOUDFLARE_API_TOKEN }}"
+    zone:       "{{ base_domain }}"
+    type:       A
+    name:       "@"
+    content:    "{{ networks.internet.ip4 }}"
+    proxied:    false
+    ttl:        1
+    state:      present
+  async: "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
+  poll:  "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"
+
+- name: "Ensure AAAA @ for {{ base_domain }} with '{{ networks.internet.ip6 | default('None') }}"
+  community.general.cloudflare_dns:
+    api_token:  "{{ CLOUDFLARE_API_TOKEN }}"
+    zone:       "{{ base_domain }}"
+    type:       AAAA
+    name:       "@"
+    content:    "{{ networks.internet.ip6 }}"
+    proxied:    false
+    ttl:        1
+    state:      present
+  when:
+    - (networks.internet.ip6 | default('') | trim) != ''
+  async: "{{ ASYNC_TIME if ASYNC_ENABLED | bool else omit }}"
+  poll:  "{{ ASYNC_POLL if ASYNC_ENABLED | bool else omit }}"