feat(11.1-05): add the walkthrough's admin controller, publish command and published_at migration

- make:admin-controller, make:command and make:migration output, finished:
  the Posts controller serves models.Post behind acme.blog.access_posts,
  WinterCMS-style form and list YAML embedded through pact.AdminAssets,
  blog:publish sets published_at by slug with a bound parameter
- the posts route lists published posts only, newest first
- Docker tests migrate an ICU pl-PL database, roll back published_at, serve
  the route and run blog:publish with a published and an opened database
- the page gains the admin controller, console command and added-column
  sections

docs/examples/blog/console/publish.go

@@ -0,0 +1,43 @@
+// Code generated by summer make. DO NOT EDIT.
+
+package console
+
+import (
+	"context"
+	"fmt"
+
+	"git.golem15.com/golem15/summercms/docs/examples/blog/models"
+	"git.golem15.com/golem15/summercms/modules/bonfire"
+	"gorm.io/gorm"
+)
+
+// PublishCommand returns the blog:publish console command. withDB runs the
+// command's work with the application's database; the plugin supplies it.
+func PublishCommand(withDB func(ctx context.Context, fn func(*gorm.DB) error) error) bonfire.Command {
+	return bonfire.Command{
+		Name:        "blog:publish",
+		Description: "Publish a blog post by its slug",
+		Args:        []bonfire.Arg{{Name: "slug", Description: "Slug of the post to publish", Required: true}},
+		Run: func(ctx context.Context, in bonfire.Input, out bonfire.Output) error {
+			slug, _ := in.Argument("slug")
+			if slug == "" {
+				return fmt.Errorf("blog:publish: a slug is required")
+			}
+			return withDB(ctx, func(db *gorm.DB) error {
+				// A bound parameter, never the slug spliced into SQL. Publishing
+				// twice keeps the first publication time.
+				res := db.WithContext(ctx).Model(&models.Post{}).
+					Where("slug = ?", slug).
+					Update("published_at", gorm.Expr("COALESCE(published_at, NOW())"))
+				if res.Error != nil {
+					return res.Error
+				}
+				if res.RowsAffected == 0 {
+					return fmt.Errorf("blog:publish: no post has the slug %q", slug)
+				}
+				out.Printf("published %s\n", slug)
+				return nil
+			})
+		},
+	}
+}