feat(diagrams): canonical animated diagram family + motion grammar; drop Obsidian references

[kengio]

Summary

1. assets/diagrams/ — the six architecture diagrams now live here canonically as animated dark/light pairs (12 SVGs) on DS tokens: transparent canvas, .cyber-card panels (never animated), at most one .btn-tech hero per diagram, dash-flow + neuron-spark motion, prefers-reduced-motion freeze, all text path-converted with glyph dedup. The three stale unpaired SVGs (coevo-loop.svg, harness-os-stack.svg, vault-hub.svg) are removed. coevo-loop is redrawn as true-circle geometry (center 225,212 · R 145 · steps at exact 120°).
2. assets/diagrams/README.md — new canonical family-grammar reference: card/hero recipes, palette map incl. the documented light-meta WCAG deviation (#0a0a1299 @ 5.16:1 over the failing --text-disabled 2.32:1), arrowhead marker standard, motion rules + reduced-motion, transparent-canvas rule, text→path pipeline (ink-bbox lockup, glyph dedup), per-diagram sizes, and the mandatory virtual-time pixel-diff test.
3. DESIGN.md §7 — short "Diagram motion" paragraph pointing at the new reference.
4. Obsidian removal — all positioning mentions in README.md + DESIGN.md replaced with plain-Markdown-vault phrasing ("Markdown Vault" layer, "the vault is the dispatch hub", checkbox task syntax); index.html/docs.html had none.
5. Skill count — 29+ → 30 everywhere (§8 sample line + product-context blurbs).
6. CHANGELOG.md — compact Unreleased entry.

Checks: node tokens/check.js ✓ (dist fresh, css↔tokens in sync) · node tokens/a11y.js ✓ (7 pairs AA) · all 12 SVGs pass the structural gates (XML, no <text>, no external refs, <120KB, reduced-motion) and the virtual-time animation proof.

Diagrams originated in onebrain repo PR #213, owner-approved through 5 template revisions.

🤖 Generated with Claude Code