style(registratie): WP-34 — BRP address as datablock, phone in grey fieldset

Restyle the contact-change form with house CIBG surfaces instead of hand-rolled
markup: the read-only BRP address now uses app-data-block/app-data-row (grey
datablock), and the phone field sits in a plain <fieldset> inside the existing
.form-horizontal form (inherits the CIBG grey box). No new CSS surfaces; row keys
reuse the address.* i18n ids. Logic/machine/specs unchanged.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/locale/messages.en.xlf

@@ -1318,6 +1318,14 @@
           <context context-type="linenumber">40,41</context>
         </context-group>
       </trans-unit>
+      <trans-unit id="changeRequest.contactLegend" datatype="html">
+        <source>Contactgegevens</source>
+        <target datatype="html">Contact details</target>
+        <context-group purpose="location">
+          <context context-type="sourcefile">src/app/registratie/ui/change-request-form/change-request-form.component.ts</context>
+          <context context-type="linenumber">88</context>
+        </context-group>
+      </trans-unit>
       <trans-unit id="changeRequest.brpAdresLabel" datatype="html">
         <source>Adres (BRP)</source>
         <target datatype="html">Address (BRP)</target>