fix(auth): restore get_user function body lost in refactor; fix button period placement

- Restore the get_user handler that was accidentally dropped when inserting
  the local user management routes before the /{user_id:path} catch-all
- Move period inside the 'Create one' button text in admin_users.html

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

frontend/templates/admin_users.html

@@ -451,7 +451,7 @@
             <tr>
               <td colspan="7" class="px-4 py-6 text-center text-gray-400">
                 No local accounts yet.
-                <button type="button" @click="openCreateLocalUserModal()" class="text-green-600 hover:underline ml-1">Create one</button>.
+                <button type="button" @click="openCreateLocalUserModal()" class="text-green-600 hover:underline ml-1">Create one.</button>
               </td>
             </tr>
           </template>