refactor(xiaoyi): refactor connection to dual WebSocket & fix unusable channel

[hongxicheng]

Summary

Refactor the XiaoYi channel from a single WebSocket connection to a
dual-connection architecture (primary domain + backup IP), and align
the A2A protocol with the official @ynhcj/xiaoyi-channel plugin.

Changes

Connection Refactor

• Extract XiaoYiConnection class to encapsulate a single WebSocket
  link (connect, heartbeat, receive, send)
• Connect to both primary (hag.cloud.huawei.com) and backup
  (116.63.174.231) endpoints in parallel
• Session-aware message routing: replies go to the server that
  delivered the request, with automatic fallback
• Reconnect only triggers when both connections are down

A2A Protocol Alignment

• Override _on_process_completed (instead of the legacy
  _run_process_loop) to send status-update(completed) +
  artifact-update(final=true) — fixes the "running" state stuck
  issue on XiaoYi App
• Init message includes msgDetail with agentId and hostname
• Heartbeat includes msgDetail with millisecond timestamp
• All artifact-update messages set lastChunk: true to match
  official plugin behavior

Configuration Simplification

• Remove user-configurable ws_url / ws_url_backup from backend
  config (XiaoYiConfig), frontend form (ChannelDrawer), and
  TypeScript types — the endpoints are fixed SaaS URLs hardcoded
  as constants
• Users only need to configure ak, sk, and agent_id
• Doctor connectivity now probes both fixed endpoints

Cleanup

• Remove unused _run_process_loop override (legacy non-queue path)
• Remove _default_backup_url() helper
• Remove DEFAULT_WS_URL / DEFAULT_WS_URL_BACKUP from
  __init__.py exports (internal constants)

Related Issue: Fixes #1911 #3840

Security Considerations: [If applicable, e.g. channel auth, env/config handling]

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

[How to test these changes]

Local Verification Evidence

pre-commit run --all-files
# paste summary result

pytest
# paste summary result

Additional Notes

[Optional: any other context]

[github-actions]

Welcome to QwenPaw! 🐾

Hi @hongxicheng, this is your 123rd Pull Request.

📋 About PR Template

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• ✅ Description - What this PR does and why
• ✅ Type of Change - Bug fix / Feature / Breaking change / Documentation / Refactoring
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• ✅ Checklist:
  • Run and pass pre-commit run --all-files
  • Run and pass relevant tests (pytest or as applicable)
  • Update documentation if needed
• ✅ Testing - How to test these changes
• ✅ Local Verification Evidence:

  pre-commit run --all-files
  # paste summary result
  
  pytest
  # paste summary result

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