fix(weixin): harden session recovery and service observability

[zggtao]

What changed

• Added iLink notifyStart / notifyStop lifecycle notifications.
• Persisted active-account and reauthorization state for safer recovery.
• Added WeChat status reporting and service-install hardening across platforms.

Why

Expired iLink sessions and stale account selection could leave the bridge appearing connected while it could not receive or reply to messages.

Validation

• WeChat login, transport, connection status, CLI, and plugin test suites passed.
• Service-script syntax checks and git diff checks passed.