feat: refactor templates to simplify base/page/form structure

to mimic what has been done in wuttaweb

tailbone/templates/purchases/credits/index.mako

@@ -59,9 +59,9 @@
 
 </%def>
 
-<%def name="modify_this_page_vars()">
-  ${parent.modify_this_page_vars()}
-  <script type="text/javascript">
+<%def name="modify_vue_vars()">
+  ${parent.modify_vue_vars()}
+  <script>
 
     ${grid.vue_component}Data.changeStatusShowDialog = false
     ${grid.vue_component}Data.changeStatusOptions = ${json.dumps(status_options)|n}
@@ -80,6 +80,3 @@
 
   </script>
 </%def>
-
-
-${parent.body()}