feat(15-02): add Posts admin with mlmarkdown and FormatHTML

YAML-driven Posts screen stores translatable markdown and regenerates
content_html in the plugin. Publish writes without access_publish are
refused; list and form queries stay on the principal without
access_other_posts.

Co-authored-by: Cursor <cursoragent@cursor.com>

admin.go

@@ -0,0 +1,37 @@
+package journal
+
+import (
+	"embed"
+	"io/fs"
+
+	"git.golem15.com/golem15/sm-journal-plugin/controllers"
+	"git.golem15.com/golem15/summercms/modules/backpack"
+	"git.golem15.com/golem15/summercms/modules/pact"
+)
+
+// adminFS holds the admin YAML and the nav SVG file by file: the controllers
+// directory also holds Go sources that are not admin assets.
+//
+//go:embed controllers/posts/config_list.yaml controllers/posts/config_form.yaml controllers/posts/config_filter.yaml models/post/fields.yaml models/post/columns.yaml
+//go:embed assets/images/journal-icon.svg
+var adminFS embed.FS
+
+func (p *Plugin) AdminFS() fs.FS { return adminFS }
+
+// AdminControllers hands the controllers a lazy accessor of the booted app,
+// so they read the database handle at request time.
+func (p *Plugin) AdminControllers() []pact.AdminController {
+	return controllers.AdminControllers(func() *backpack.App {
+		if p == nil {
+			return nil
+		}
+		return p.app
+	})
+}
+
+var (
+	_ pact.AdminAssets         = (*Plugin)(nil)
+	_ pact.HasAdminControllers = (*Plugin)(nil)
+	_ pact.HasPermissions      = (*Plugin)(nil)
+	_ pact.HasNavigation       = (*Plugin)(nil)
+)