feat: H1 conversion on the API, markdown and import paths

- the /_journal/api/v1 post writes convert default and translated content
  in the write transaction and answer an additive notices key
- journal:import-posts converts and prints the converted count
  (ImportFromDirConfig, ImportStats.H1Converted)
- a category's pillar text saved in the admin answers
  editor.h1_converted_category
- every GET /categories row reports content_h1_to_h2 (additive key)

console/export_posts.go

@@ -13,6 +13,7 @@ import (
 	translatemodels "git.golem15.com/golem15/sm-translate-plugin/models"
 	"git.golem15.com/golem15/summercms/modules/backpack"
 	"git.golem15.com/golem15/summercms/modules/bonfire"
+	"git.golem15.com/golem15/summercms/modules/compass"
 	"gorm.io/gorm"
 )
 
@@ -251,6 +252,14 @@ func isEmptyValue(v any) bool {
 	return ok && s == ""
 }
 
+// appConfig is app's config, nil without an application.
+func appConfig(app *backpack.App) *compass.Config {
+	if app == nil {
+		return nil
+	}
+	return app.Config
+}
+
 func mustDB(app *backpack.App) *gorm.DB {
 	if app == nil {
 		return nil