fix(channel): telegram network retry

[Leirunlin]

Description

This change makes TelegramChannel handle polling failures more explicitly instead of relying on PTB internals alone. It now:

• detects polling network error vs conflict
• tracks consecutive retries separately for each case
• requests a clean outer reconnect by stopping the updater and rebuilding the application
• applies reason-specific retry delays:
  • network errors: exponential backoff
  • conflicts: fixed delay

This fixes the case where Telegram stops receiving messages after a brief disconnect and only recovers after manually restarting QwenPaw or toggling the channel.

Related Issue: Fixes #4017

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation
• Refactoring

Component(s) Affected

• Core / Backend (app, agents, config, providers, utils, local_models)
• Console (frontend web UI)
• Channels (DingTalk, Feishu, QQ, Discord, iMessage, etc.)
• Skills
• CLI
• Documentation (website)
• Tests
• CI/CD
• Scripts / Deploy

Checklist

• I ran pre-commit run --all-files locally and it passes
• If pre-commit auto-fixed files, I committed those changes and reran checks
• I ran tests locally (pytest or as relevant) and they pass
• Documentation updated (if needed)
• Ready for review

For Channel Changes (DingTalk, Feishu, QQ, Console, etc.)

• I ran ./scripts/check-channels.sh (or ./scripts/check-channels.sh --changed) and it passes
• Contract test exists in tests/contract/channels/test_<channel>_contract.py (REQUIRED)
• Contract test implements create_instance() with proper channel initialization
• All 19 contract verification points pass (see tests/contract/channels/__init__.py)
• Optional: Unit tests in tests/unit/channels/test_<channel>.py for complex internal logic

Testing

I test it manually. It now reconnects successfully when QwenPaw encounters a network issue.

[github-actions]

Welcome to QwenPaw! 🐾

Hi @Leirunlin, this is your 58th Pull Request.

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Thanks so much for your contribution! We'd love to invite you to join the official QwenPaw developer group! You can find the Discord and DingTalk group links under the "Developer Community" section on our docs page:
https://qwenpaw.agentscope.io/docs/community

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