feat: add custom field slug

lib/mv_web/live/custom_field_live/show.ex

@@ -9,6 +9,8 @@ defmodule MvWeb.CustomFieldLive.Show do
   - Return to custom field list
 
   ## Displayed Information
+  - ID: Internal UUID identifier
+  - Slug: URL-friendly identifier (auto-generated, immutable)
   - Name: Unique identifier
   - Value type: Data type constraint
   - Description: Optional explanation
@@ -29,7 +31,7 @@ defmodule MvWeb.CustomFieldLive.Show do
     ~H"""
     <Layouts.app flash={@flash} current_user={@current_user}>
       <.header>
-        Custom field {@custom_field.id}
+        Custom field {@custom_field.slug}
         <:subtitle>This is a custom_field record from your database.</:subtitle>
 
         <:actions>
@@ -48,6 +50,8 @@ defmodule MvWeb.CustomFieldLive.Show do
       <.list>
         <:item title="Id">{@custom_field.id}</:item>
 
+        <:item title="Slug">{@custom_field.slug}</:item>
+
         <:item title="Name">{@custom_field.name}</:item>
 
         <:item title="Description">{@custom_field.description}</:item>