feat(dns): add sys-svc-dns role and extend parent DNS handling

Introduce sys-svc-dns to bootstrap Cloudflare DNS prerequisites. Validates CLOUDFLARE_API_TOKEN, (optionally) manages CAA for base SLDs, and delegates parent record creation to sys-dns-parent-hosts. Wired into sys-stk-front-pure.

sys-dns-parent-hosts: new parent_dns filter builds A/AAAA for each parent host and wildcard children (*.parent). Supports dict/list inputs for CURRENT_PLAY_DOMAINS, optional IPv6, proxied flag, and optional *.apex. Exposes a single parent_build_records entry point.

Let’s Encrypt role cleanup: remove DNS/C AA management from sys-svc-letsencrypt; it now focuses on webroot challenge config and renew timer. Fixed path joins and run_once guards.

Tests: update unit tests to allow wildcard outputs and dict-based CURRENT_PLAY_DOMAINS. Add generate_base_sld_domains filter. Documentation updates for both roles.

Conversation: https://chatgpt.com/share/68c342f7-d20c-800f-b61f-cefeebcf1cd8

roles/sys-dns-parent-hosts/README.md

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+# sys-dns-parent-hosts
+
+Create Cloudflare DNS A/AAAA records only for **parent hosts** (hosts that have children),
+and always include the **apex** (SLD.TLD) as a parent.
+
+Examples:
+- c.wiki.example.com  -> parent: wiki.example.com
+- a.b.example.com     -> parent: b.example.com
+- example.com (apex)  -> always included
+
+## Inputs
+- parent_dns_domains (list[str], optional): FQDNs to evaluate. If empty, the role flattens CURRENT_PLAY_DOMAINS.
+- PRIMARY_DOMAIN (apex), defaults_networks.internet.ip4, optional defaults_networks.internet.ip6
+- Flags:
+  - parent_dns_enabled (bool, default: true)
+  - parent_dns_ipv6_enabled (bool, default: true)
+  - parent_dns_proxied (bool, default: false)
+
+## Usage
+- Include the role once after your constructor stage has set CURRENT_PLAY_DOMAINS.
+
+## Tests
+Unit tests: tests/unit/roles/sys-dns-parent-hosts/filter_plugins/test_parent_dns.py
+Run with: pytest -q