feat(11.1-05): add the acme.blog walkthrough plugin with its model, migration and posts route

- docs/examples/blog: scaffolder output for acme.blog (make:plugin, make:model)
  in the root module, with a Post model, a fill allow-list and NewPost, the
  create migration and GET /api/blog/posts paginated through lagoon
- short tests activate the plugin, check the route with surf, the fill
  allow-list and the migration order
- docs/setup/porting-a-plugin.md: registration, model, migrations and routes
  sections with src= copies of the plugin
- TestDocsRequiredPages requires setup/porting-a-plugin

docs/examples/blog/updates/20260101000000_create_acme_blog_posts.go

@@ -0,0 +1,28 @@
+// Code generated by summer make. DO NOT EDIT.
+
+package updates
+
+import (
+	"github.com/go-gormigrate/gormigrate/v2"
+	"gorm.io/gorm"
+)
+
+// CreatePosts returns the 20260101000000_create_acme_blog_posts gormigrate entry.
+func CreatePosts() *gormigrate.Migration {
+	return &gormigrate.Migration{
+		ID: "20260101000000_create_acme_blog_posts",
+		Migrate: func(tx *gorm.DB) error {
+			return tx.Exec(`CREATE TABLE acme_blog_posts (
+    id BIGSERIAL PRIMARY KEY,
+    title VARCHAR(255) NOT NULL,
+    slug VARCHAR(255) NOT NULL UNIQUE,
+    body TEXT NOT NULL DEFAULT '',
+    created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+    updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+)`).Error
+		},
+		Rollback: func(tx *gorm.DB) error {
+			return tx.Exec("DROP TABLE IF EXISTS acme_blog_posts").Error
+		},
+	}
+}