feat(email-domains): support creating email domains on optional subdomains

ts_web/elements/email/ops-view-email-domains.ts

@@ -276,6 +276,11 @@ export class OpsViewEmailDomains extends DeesElement {
             .options=${domainOptions}
             .required=${true}
           ></dees-input-dropdown>
+          <dees-input-text
+            .key=${'subdomain'}
+            .label=${'Subdomain'}
+            .description=${'Leave empty for bare domain, e.g. "mail" for mail.example.com'}
+          ></dees-input-text>
           <dees-input-text
             .key=${'dkimSelector'}
             .label=${'DKIM Selector'}
@@ -316,10 +321,12 @@ export class OpsViewEmailDomains extends DeesElement {
                 ? parseInt(data.dkimKeySize.key, 10)
                 : parseInt(data.dkimKeySize || '2048', 10);
 
+            const subdomain = data.subdomain?.trim() || undefined;
             await appstate.emailDomainsStatePart.dispatchAction(
               appstate.createEmailDomainAction,
               {
                 linkedDomainId,
+                subdomain,
                 dkimSelector: data.dkimSelector || 'default',
                 dkimKeySize: keySize,
                 rotateKeys: Boolean(data.rotateKeys),