docs(contest): link official velaclaw API reference & move D13x to supported boards

[tanghao-xiaomi]

Changes

• quickapp_velaclaw.md: add a reference to the official system.velaclaw API doc in section "六、在快应用中调用 velaclaw", as the authoritative source for the interface spec.
• supported_hardware.md: move "D13x 系列 EVM 评估板 — 匠芯创" from "待适配" (to-be-ported) to "已支持" (supported) as item 11, right after its sibling D12x; remaining to-be-ported items renumbered accordingly.

TODO

• The D13x "开发指南" (dev guide) link is a placeholder for now, pending the D13x-specific README path from the development team.

Notes

• Rebased onto the latest dev-ai-contest-2026.