docs: add TweetClaw source packet recipe

[kriptoburak]

需求理解 / Requirement Understanding

用 1-2 句话复述你对需求的理解。Reviewer 会优先检查这里是否正确，方向不对直接打回。

我理解的需求是：
Document a safe OpenClaw handoff for reviewed public X/Twitter items collected with TweetClaw, so ClawFeed users can feed those items into the existing custom API and source-pack model without adding automatic account actions.

原始指令/Issue：
No issue. This is a documentation-only contribution based on the existing Twitter source and custom API support.

---

Summary

• Adds docs/tweetclaw-source-packet.md with a reviewed source-packet shape for TweetClaw X/Twitter reads.
• Links the recipe from README source types and SKILL.md.
• Documents attribution, deduplication, and approval boundaries so ClawFeed stays focused on digest generation.

Type

• Feature
• Bug fix
• Refactor
• CI / DevOps
• Docs

Test plan

• npm test passes
• npm run lint passes with 0 errors and 5 pre-existing warnings in source files
• Manual verification: Markdown link check for README, SKILL.md, and the new recipe doc
• Manual verification: git whitespace check, conflict-marker scan, and added-line public-hygiene scan
• Manual verification: npm metadata for @xquik/tweetclaw returned the current OpenClaw install metadata

Checklist

• No secrets or credentials committed
• No console.log left in production code
• Breaking changes documented (if any)