feat(add-wechat): personal WeChat channel via Tencent iLink Bot API

New channel skill for personal WeChat, using Tencent's official iLink
Bot API (the same protocol @tencent-weixin/openclaw-weixin uses).
Region-restricted to mainland 微信 accounts — international WeChat
clients can't complete the QR flow.

Skill contents:
- Install steps copy the adapter from the `channels` branch (same
  pattern as other /add-<channel> skills) and register it in
  src/channels/index.ts.
- Post-login wiring helper at scripts/wire-dm.ts — lists unwired
  WeChat messaging groups, prompts for an agent group, and inserts the
  messaging_group_agents row with sender policy `request_approval` by
  default (matches the router auto-create default so the admin gets an
  approval card on the next unknown-sender DM).
- Channel Info documents how /new-setup Claude captures the
  operator's user_id (from data/wechat/auth.json.operatorUserId) and
  the first DM's platform_id (from the adapter's "WeChat inbound" log).

Also adds WeChat as option 15 in /new-setup's channel list so setup
wires into the existing /add-<channel> flow automatically.

Addresses https://github.com/qwibitai/nanoclaw/issues/1901.

Co-Authored-By: ythx-101 <226337373+ythx-101@users.noreply.github.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.claude/skills/new-setup/SKILL.md

@@ -189,6 +189,7 @@ Print the list as a numbered plain-prose list (too many options for `AskUserQues
 > 12. **Webex** — `/add-webex`
 > 13. **Resend (email)** — `/add-resend`
 > 14. **Emacs** — `/add-emacs`
+> 15. **WeChat** — `/add-wechat`
 >
 > Or say "skip" to leave this for later.