Add XiuRouter to AI Inference & Model APIs

[MuduiClaw]

Summary

Adds XiuRouter to the AI Inference & Model APIs category with one alphabetized README entry. The description is intentionally neutral and limited to publicly verifiable product capabilities.

I am submitting this on behalf of XiuLab Inc, the operator of XiuRouter.

Inclusion criteria

• Transparent public pricing: https://router.xiu.ai/en/pricing/
• Usage-based self-service: https://router.xiu.ai/en/console/keys
• Public production status: https://router-api.xiu.ai/status

Validation

• npx prettier --check README.md
• python3 scripts/parse_readme_to_json.py README.md /tmp/xiurouter-alt-clouds-clouds.json
• Parsed output contains exactly one XiuRouter entry in AI Inference & Model APIs with score 3
• python3 -m pytest tests/test_readme_entries.py tests/test_check_duplicates.py -q (77 passed)
• git diff --check

npm run build currently reaches static route generation and then fails on four pre-existing orphan MDX profiles (blacksmith, conecto, hikube, and superset) that do not match the current upstream clouds.json; this PR only changes one README line.

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[cla-assistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

wangshufu seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}