feat: add <kindred> element to package.xml

Declares min_create_version=0.1.0, load_priority=50, pure_python=true,
and documents partdesign.body/feature context injection.

package.xml

@@ -29,4 +29,15 @@
     </preferencepack>
   </content>
 
+  <!-- Kindred Create extensions -->
+  <kindred>
+    <min_create_version>0.1.0</min_create_version>
+    <load_priority>50</load_priority>
+    <pure_python>true</pure_python>
+    <contexts>
+      <context id="partdesign.body" action="inject"/>
+      <context id="partdesign.feature" action="inject"/>
+    </contexts>
+  </kindred>
+
 </package>