feat(15-01): add journal en/pl phrasebooks and plugin README

Operators get UI catalogs for plugin, journal, post, category, and tag
keys, plus an application-neutral README for the compiled plugin.

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

plugin.go

@@ -1,6 +1,9 @@
 package journal
 
 import (
+	"embed"
+	"io/fs"
+
 	"git.golem15.com/golem15/sm-journal-plugin/models"
 	"git.golem15.com/golem15/sm-journal-plugin/updates"
 	"git.golem15.com/golem15/summercms/modules/backpack"
@@ -13,8 +16,12 @@ var (
 	_ party.Plugin       = (*Plugin)(nil)
 	_ pact.HasMigrations = (*Plugin)(nil)
 	_ pact.HasModels     = (*Plugin)(nil)
+	_ pact.HasLang       = (*Plugin)(nil)
 )
 
+//go:embed lang
+var langFS embed.FS
+
 // Plugin is the golem15.journal plugin.
 type Plugin struct {
 	app *backpack.App
@@ -34,6 +41,8 @@ func (p *Plugin) Boot(app *backpack.App) error {
 	return nil
 }
 
+func (p *Plugin) LangFS() fs.FS { return langFS }
+
 func (p *Plugin) Migrations() []*gormigrate.Migration { return updates.All() }
 
 func (p *Plugin) Models() []any { return models.All() }