feat(11.1-05): pin the walkthrough to the scaffolder and link it from the concept map

- TestScaffoldLayout runs make:plugin, make:model, make:migration,
  make:admin-controller and make:command for acme.blog in a copy of
  examples/hello and compares the file set with docs/examples/blog
- the page lists the exact make commands, the go.mod a scaffolded plugin
  gets, what the scaffolder leaves to the developer and a checklist
- scaffolding.md no longer claims same-second migrations get consecutive
  timestamps; only same-name ones do
- coming-from-wintercms.md and index.md link the walkthrough

docs/setup/coming-from-wintercms.md

@@ -10,6 +10,8 @@ SummerCMS keeps the parts of WinterCMS that make a plugin developer productive.
 
 What changes is everything that depends on PHP at runtime. Plugins are Go packages compiled into one binary, so there is no plugin directory scanned at boot and no runtime autoloading. Magic methods, dynamic properties and behaviours give way to Go interfaces and composition. SummerCMS is headless: it serves a JSON API and the admin SPA, and the frontend is a separate application that calls that API.
 
+This page maps the concepts. To see them applied to one plugin from start to finish, follow [Porting a plugin](porting-a-plugin.md), which takes an `acme/blog` plugin with a model, migrations, a route, a backend controller and a console command to SummerCMS.
+
 ## Concept map
 
 Each row names the WinterCMS concept, the SummerCMS identifiers that replace it, and where to read more: the guide page first, then the module reference.