feat(catalog): class template editing

Templates were delete-and-recreate only. Adds PUT
/v1/catalog/class-templates/{id} across repository, service (sharing
the create-time validation), route, spec, and client; the classes tab
gets a pencil action that loads the row into the form with a
save/cancel affordance.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

apps/frontend/src/components/dashboard/icons.tsx

@@ -114,6 +114,12 @@ export const PlusIcon = () => (
   </svg>
 );
 
+export const PencilIcon = () => (
+  <svg xmlns="http://www.w3.org/2000/svg" width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round">
+    <path d="M12 20h9"/><path d="M16.5 3.5a2.121 2.121 0 0 1 3 3L7 19l-4 1 1-4L16.5 3.5"/>
+  </svg>
+);
+
 export const ScissorsIcon = () => (
   <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round">
     <circle cx="6" cy="6" r="3"/><path d="M8.12 8.12 12 12"/><path d="M20 4 8.12 15.88"/><circle cx="6" cy="18" r="3"/><path d="M14.8 14.8 20 20"/>