feat: replace Dynamic DNS YAML editor with a web form

Adds structured form fields for nsupdate_bin, rndc_key, and dyndomains
(comma-separated list). Wires list-type editable fields through the
generic stageFormSection path and adds DNS support to
apply_structured_section in configio.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hbd/server/configio.py

@@ -88,6 +88,12 @@ def apply_structured_section(data, section: str, values: dict) -> None:
         for key in _SERVER_KEYS:
             if key in values:
                 data[key] = values[key]
+    elif section == "dns":
+        for key in _DNS_KEYS:
+            if key in values:
+                data[key] = values[key]
+            else:
+                data.pop(key, None)
     elif section == "users":
         data["users"] = values
     elif section == "hosts":

hbd/server/http.py

@@ -1304,9 +1304,15 @@ async def start(
                             attrs.pop("client_secret", None)
                 data["oauth"] = new_oauth
 
-            for section in ("notification_channels", "dns"):
-                if section in payload:
-                    configio_mod.apply_yaml_section(data, section, payload[section])
+            if "notification_channels" in payload:
+                configio_mod.apply_yaml_section(data, "notification_channels", payload["notification_channels"])
+
+            if "dns" in payload:
+                dns_payload = payload["dns"]
+                if isinstance(dns_payload, str):
+                    configio_mod.apply_yaml_section(data, "dns", dns_payload)
+                else:
+                    configio_mod.apply_structured_section(data, "dns", dns_payload)
 
             if "thresholds" in payload:
                 tc = payload["thresholds"]

hbd/server/settings.py

@@ -398,10 +398,18 @@ def get_settings_sections(config: dict, threshold_checker=None) -> list:
         {
             "id": "dns",
             "title": "Dynamic DNS",
-            "description": "nsupdate-based DNS registration — edit raw YAML.",
-            "section_mode": "yaml",
+            "description": "nsupdate-based DNS registration via nsupdate(8).",
+            "section_mode": "form",
             "api_section": "dns",
-            "fields": [],
+            "fields": [
+                field("nsupdate_bin", "nsupdate binary", "path",
+                      "Path to the nsupdate binary.", editable=True),
+                field("rndc_key", "RNDC key file", "path",
+                      "Path to the rndc key file used to authenticate DNS updates.", editable=True),
+                field("dyndomains", "Dynamic domains", "list",
+                      "Domains updated via nsupdate when a host with dyndns: true reports in.",
+                      editable=True),
+            ],
         },
         {
             "id": "users",

hbd/server/templates/settings.html

@@ -820,6 +820,11 @@
                     <input type="number" class="field-input"
                            data-key="{{ f.key }}" data-type="{{ f.type }}" data-section="{{ section.api_section }}"
                            value="{{ f.raw if f.raw is not none else '' }}">
+                  {% elif f.type == 'list' %}
+                    <input type="text" class="field-input"
+                           data-key="{{ f.key }}" data-type="list" data-section="{{ section.api_section }}"
+                           value="{{ f.value | join(', ') if f.value else '' }}"
+                           placeholder="comma-separated">
                   {% else %}
                     <input type="text" class="field-input"
                            data-key="{{ f.key }}" data-section="{{ section.api_section }}"
@@ -1023,6 +1028,8 @@
           } else if (el.dataset.type === 'number' || el.dataset.type === 'port') {
             const v = parseInt(el.value, 10);
             _staged[apiSection][key] = isNaN(v) ? null : v;
+          } else if (el.dataset.type === 'list') {
+            _staged[apiSection][key] = el.value.split(',').map(s => s.trim()).filter(Boolean);
           } else {
             _staged[apiSection][key] = el.value;
           }