fix(i18n): publish the translation bundle only once it is complete

InitLocalizer filled the shared bundle in place, and the Telegram bot
runs it again while the panel is serving, so a request could read the
bundle's maps while they were being written and the process died on a
concurrent map access. Build the bundle privately and publish it, and
the bot and web localizers, through atomic pointers; the lazy load in
the middleware publishes only if nothing else did first.

internal/web/service/tgbot/tgbot_draft_render_test.go

@@ -52,9 +52,8 @@ func draftLocalizer(t *testing.T, msgs ...*i18n.Message) {
 	bundle := i18n.NewBundle(language.MustParse("en-US"))
 	bundle.RegisterUnmarshalFunc("json", json.Unmarshal)
 	_ = bundle.AddMessages(language.MustParse("en-US"), msgs...)
-	orig := locale.LocalizerBot
-	t.Cleanup(func() { locale.LocalizerBot = orig })
-	locale.LocalizerBot = i18n.NewLocalizer(bundle, "en-US")
+	orig := locale.SwapBotLocalizer(i18n.NewLocalizer(bundle, "en-US"))
+	t.Cleanup(func() { locale.SwapBotLocalizer(orig) })
 }
 
 // Regression test: the wizard's own prompts are HTML-parsed as well, so the