feat: add hallmark design skill

Anti-AI-slop design skill (greenfield pages, audits, redesigns, design
extraction from URLs/screenshots) -- installed and validated in an
earlier session, was sitting untracked. Full reference library:
components, macrostructures, themes, genres, verbs (audit/redesign).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

skills/hallmark/references/components/c1-outlined-chip.md

@@ -0,0 +1,12 @@
+
+### C1 · Outlined chip
+A bordered, transparent button with a typographic verb ("Save changes").
+*Use when:* the page has one primary action; you want it visible but quiet.
+*Don't confuse with:* C2 Oversized solid (which is statement-loud).
+
+```html
+<a class="cta-outline">Open your studio →</a>
+```
+```css
+.cta-outline { display: inline-flex; align-items: center; gap: 0.4em; padding: 0.7rem 1.2rem; border: 1px solid var(--color-ink); min-height: 44px; }
+```