feat: add cmk:blueprint-animation design skill

[harrymove-ctrl]

What

Ports moguzbulbul/blueprint-animation v1.3.1 (29aa30b) into the kit as cmk:blueprint-animation, the first skill in a new Design family: one continuous blueprint animation that explains UX decisions step by step. Redesign mode takes Before + After screens; Explain mode takes one screen.

⚠️ License: needs a maintainer decision before merge

Upstream is CC BY-NC 4.0: non-commercial use only, and commercial use needs the author's written permission. This repo is MIT, and the site deploys from it.

• The package carries its own skills/blueprint-animation/LICENSE, the upstream legal code copied verbatim. SKILL.md, every reference file, the README row, and the docs/ai map all say CC BY-NC 4.0 and credit the author.
• The root LICENSE and .claude-plugin/plugin.json ("license": "MIT") are unchanged. Read without qualification, they now claim MIT for this directory too.
• Before merging, confirm that ai-devkit's distribution counts as non-commercial, or get written permission from @moguzbulbul. If neither works, close this PR.

Adaptation to house style

• Frontmatter uses name: cmk:blueprint-animation, description, and version: 0.1.0. The upstream license: key was dropped because the lint allows only these fields.
• SKILL.md was 182 lines upstream and is 95 here, within the 150-line budget. Upstream §0–8 numbering is kept so cross-references still resolve:
  • SKILL.md: §0 fidelity, §1 gather/mode, §2 per-step sequence, §7 QA
  • references/blueprint-style.md: §3–4
  • references/architecture.md: §5–6
  • references/explain-mode.md: §8
  • references/example-scene.jsx: upstream reference scene, verbatim
• The version banner now reads the version from the frontmatter, so it can't drift from it.
• The skill text is otherwise unchanged.

Site / docs

• lib/skill-types.ts gets a new design category ("Design"), a category mapping, and a card purpose line.
• lib/skill-graph-layout.ts gets a design lane after sui. LAYOUT_VERSION goes from 3 to 4 because the lanes below it move.
• README.md adds a Design family table. docs/ai/skills/ adds the new map blueprint-animation.md, an index entry, and a Design-family paragraph in conventions.md.

Verification

• bash scripts/skill-lint.sh → OK
• npm run lint → no warnings; npm run type-check → OK; npm run build → 35 /skills/[skillId] pages
• next start smoke test: /skills/blueprint-animation and /workspace return 200 and list example-scene.jsx, explain-mode.md, and LICENSE. The /skills payload shows "category":"design","categoryLabel":"Design".