feat(approval): 审批改用 TG 原生 inline keyboard 按钮

- 审批请求以「✅ 允许一次 / ❌ 拒绝」双按钮消息呈现，点按钮即裁决并 toast 确认
- 按钮发送失败自动降级为原文本提示（回复 A/B），审批绝不丢失
- 文本作答通道保留（handleTgApproval 的 A/B 解析不变），/cancel 语义不变

lib/bridge.d.ts

@@ -144,6 +144,9 @@ export declare class TelegramBridge {
     private handleAskCallback;
     private installApprovalInterceptor;
     private aroundApprovalRequest;
+    /** Approval prompt as native inline-keyboard buttons; falls back to a plain-text prompt. */
+    private deliverApprovalPrompt;
+    private handleApprovalCallback;
     private handleTgApproval;
     private stopBound;
     private sendMission;