fix: import typing callbacks from compatible SDK path

[AmAzing129]

Summary

• import createTypingCallbacks from openclaw/plugin-sdk/channel-reply-pipeline
• preserve compatibility with the declared minimum host (openclaw >=2026.5.12)
• restore compatibility with current hosts that no longer export plugin-sdk/channel-runtime

Problem

@tencent-weixin/openclaw-weixin@2.4.6 currently imports createTypingCallbacks from openclaw/plugin-sdk/channel-runtime. OpenClaw removed that package export in 2026.7.2-beta.4, so the Weixin provider exits at startup on newer hosts with:

Package subpath './plugin-sdk/channel-runtime' is not defined by "exports"

This was reproduced with OpenClaw 2026.8.1-beta.2: the channel repeatedly restarted and never received messages.

channel-reply-pipeline is exported by both the plugin's minimum supported host (2026.5.12) and 2026.8.1-beta.2, and exports the same createTypingCallbacks helper. channel-outbound would be canonical on current hosts, but is not exported by 2026.5.12, so using it would break the existing compatibility contract.

Related OpenClaw report: openclaw/openclaw#115478

Verification

• npm run typecheck against openclaw@2026.5.12
• npm run build
• verified createTypingCallbacks resolves from channel-reply-pipeline on openclaw@2026.8.1-beta.2
• all 397 Vitest cases pass; the repository's coverage command still exits non-zero because branch coverage is 89.13% against the configured 90% threshold (process-message.ts is excluded from coverage)

[scotthuang]

Independent verification on 2026-08-28:

• On OpenClaw 2026.8.1, importing openclaw/plugin-sdk/channel-runtime reproduces ERR_PACKAGE_PATH_NOT_EXPORTED.
• openclaw/plugin-sdk/channel-reply-pipeline exports createTypingCallbacks on both the declared minimum host (2026.5.12) and current 2026.8.1.
• The canonical channel-outbound path is not exported by 2026.5.12 (it first appears in 2026.5.27), so this PR's compatibility bridge is preferable to raising the plugin's minimum host version for a one-line repair.
• At exact head 82dc70c5e79c678f810b55b13dad7f2524eede90: npm run typecheck, npm run build, and all 397 Vitest cases with coverage disabled pass locally.

This is the compatibility-preserving fix for current hosts while retaining the package's documented openclaw >=2026.5.12 support.