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/plugin.go

@@ -0,0 +1,68 @@
+package blog
+
+import (
+	"embed"
+	"io/fs"
+
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/bonfire"
+	"git.golem15.com/golem15/summercms/modules/pact"
+	"git.golem15.com/golem15/summercms/modules/party"
+	"github.com/go-gormigrate/gormigrate/v2"
+)
+
+var (
+	_ pact.HasConfig           = (*Plugin)(nil)
+	_ pact.HasLang             = (*Plugin)(nil)
+	_ pact.HasMailTemplates    = (*Plugin)(nil)
+	_ pact.HasModels           = (*Plugin)(nil)
+	_ pact.HasMigrations       = (*Plugin)(nil)
+	_ pact.HasCommands         = (*Plugin)(nil)
+	_ pact.HasJobs             = (*Plugin)(nil)
+	_ pact.HasAdminControllers = (*Plugin)(nil)
+)
+
+//go:embed config
+var configFS embed.FS
+
+//go:embed lang
+var langFS embed.FS
+
+//go:embed views/mail
+var mailFS embed.FS
+
+// Plugin is the acme.blog plugin, the Go form of Plugin.php.
+type Plugin struct {
+	app *backpack.App
+}
+
+func (p *Plugin) ID() string         { return "acme.blog" }
+func (p *Plugin) Requires() []string { return nil }
+
+func (p *Plugin) Register(*backpack.App) error { return nil }
+
+// Boot keeps the application, so route handlers and commands can reach its
+// services, such as the database, when they run.
+func (p *Plugin) Boot(app *backpack.App) error {
+	p.app = app
+	return nil
+}
+
+func (p *Plugin) ConfigFS() fs.FS { return configFS }
+func (p *Plugin) LangFS() fs.FS   { return langFS }
+
+func (p *Plugin) MailTemplatesFS() fs.FS         { return mailFS }
+func (p *Plugin) MailTemplates() []string        { return nil }
+func (p *Plugin) MailLayouts() map[string]string { return nil }
+
+func (p *Plugin) Models() []any                       { return generatedModels() }
+func (p *Plugin) Migrations() []*gormigrate.Migration { return generatedMigrations() }
+func (p *Plugin) Commands() []bonfire.Command         { return generatedCommands() }
+func (p *Plugin) Jobs() []pact.Job                    { return generatedJobs() }
+func (p *Plugin) AdminControllers() []pact.AdminController {
+	return generatedAdminControllers()
+}
+
+func init() {
+	party.Register(&Plugin{})
+}