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/h6-photographic-fold.md

@@ -0,0 +1,16 @@
+### H6 · Photographic Fold
+Single full-bleed image fills the viewport. Caption sits in a corner.
+*Use when:* you have real photography that earns full-bleed.
+*Don't confuse with:* H2 Split (which pairs image with text in a grid).
+
+```html
+<section class="hero-photo">
+  <img class="bleed" src="" alt="" />
+  <p class="caption">Spring, 2026.</p>
+</section>
+```
+```css
+.hero-photo { position: relative; height: 80dvh; }
+.hero-photo .bleed { width: 100%; height: 100%; object-fit: cover; }
+.hero-photo .caption { position: absolute; bottom: var(--space-md); right: var(--space-md); }
+```