feat: add Manus skillsmp registry and multi-registry publishing support

[dongjiang1989]

Summary

• Add SkillsMP registry as a new distribution channel

Closes: #55

📦 Available Registries

Registry	URL
iFLYTEK Skillhub (Official)	skill.xfyun.cn
ClawHub	clawhub.ai/user/iflytek.skills
Skills.sh	skills.sh/iflytek/ifly-skills
SkillHub (Tencent Cloud)	skillhub.cloud.tencent.com
SkillsMP	skillsmp.com/creators/iflytek

⚠️ Notice:
skillsmp registry automatically indexes compliant Skills hosted in public GitHub repositories, so there is no need to submit GitHub Actions workflows.

[FenjuFu]

Thanks for adding the SkillsMP registry — the README/README_zh changes look good. 👍

One issue blocks the merge: this PR also deletes CLA.md (−22 lines), which isn't mentioned in the description and is unrelated to adding a registry link. CLA.md was added recently in 6eaffe8e together with the CLA Assistant workflow, and the repo still runs a license/cla check — removing the file would drop the project's Contributor License Agreement.

This looks like a stale-branch artifact (the branch was likely created before CLA.md landed). Could you please:

1. Rebase add-skillsmp onto the latest main, and
2. Restore CLA.md so the only change is the SkillsMP registry row?

Once CLA.md is back and the diff contains only the README additions, this is good to merge.

[dongjiang1989]

@FenjuFu F We have migrated CLA signing to https://cla-assistant.io/. CLA.md is an unnecessary file.

[FenjuFu]

Thanks for the heads-up. Agreed — since CLA signing now goes through cla-assistant.io, the in-repo CLA bits are redundant. CLA.md is already removed in this PR (#56). The self-hosted CLA Assistant (.github/workflows/cla.yml + signatures/version1/cla.json) can be dropped too whenever convenient — happy to send a follow-up PR to clean those up if you'd like.

[dongjiang1989]

@FenjuFu
The .github/workflows/cla.yml and signatures/version1/cla.json files have already been removed in previous PRs.
This PR cleans up the remaining CLA.md files related to CLA.

[FenjuFu]

Verified that .github/workflows/cla.yml and signatures/version1/cla.json are already gone from main and CLA signing runs through cla-assistant.io (license/cla check passing). Removing the orphaned CLA.md is consistent. Diff is clean — only the SkillsMP registry row plus the CLA.md cleanup. LGTM.