Support Codex 0.134 approvals

Use available approval decisions from the app-server schema, preserve structured policy decisions in callbacks, and keep approval rendering aligned with normal tool-call output.

Also simplify thread commands, clear stale active turns more carefully, and update command/help docs.

internal/telegram/types.go

@@ -74,3 +74,8 @@ type EditMessageTextOptions struct {
 	ParseMode   string                `json:"parse_mode,omitempty"`
 	ReplyMarkup *InlineKeyboardMarkup `json:"reply_markup,omitempty"`
 }
+
+type BotCommand struct {
+	Command     string `json:"command"`
+	Description string `json:"description"`
+}