Fold X Chat into the always-read X MCP guide

[vaulpannx]

Summary

• Move encrypted X Chat (inbox / DMs / helper clone / PIN) into the X MCP guide skill GrokBot already loads. Agents clone `xchat-grokbot-helper` themselves instead of waiting to be told to find a second skill or the helper repo.
• Remove `skills/x-chat/`. Bump the plugin to 2.5.1; leave the shipped 2.5.0 companion-skill changelog intact.

Test plan

• Connect X: same credits / capabilities flow as 2.5.0, including the Chat bullet.
• Ask about inbox / X Chat / DMs without naming the helper: agent clones `xchat-grokbot-helper` (or reuses `$HOME/xchat-lite`) and secret-requests Chat PIN — does not ask the user to find `x-chat` or `xchat_lite.py`.
• Other X tools work but Chat tools missing: reconnect copy, not Project/App.
• `--user-id` is the X id from `get_users_me`, not the shell `$UID`.

Made with Cursor

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