refactor(skills): move site-architecture catalogs to references

Keep the decision steps in SKILL.md and move catalogs, examples, and
checklists verbatim to references/ to reduce the context cost of loading the
skill.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/skills/site-architecture/references/visual-sitemaps.md

@@ -0,0 +1,48 @@
+# Visual Sitemap Output (Mermaid)
+
+Use Mermaid `graph TD` for visual sitemaps. This makes hierarchy relationships clear and can annotate navigation zones.
+
+## Basic Hierarchy
+
+```mermaid
+graph TD
+    HOME[Homepage] --> FEAT[Features]
+    HOME --> PRICE[Pricing]
+    HOME --> BLOG[Blog]
+    HOME --> ABOUT[About]
+
+    FEAT --> F1[Analytics]
+    FEAT --> F2[Automation]
+    FEAT --> F3[Integrations]
+
+    BLOG --> B1[Post 1]
+    BLOG --> B2[Post 2]
+```
+
+## With Navigation Zones
+
+```mermaid
+graph TD
+    subgraph Header Nav
+        HOME[Homepage]
+        FEAT[Features]
+        PRICE[Pricing]
+        BLOG[Blog]
+        CTA[Get Started]
+    end
+
+    subgraph Footer Nav
+        ABOUT[About]
+        CAREERS[Careers]
+        CONTACT[Contact]
+        PRIVACY[Privacy]
+    end
+
+    HOME --> FEAT
+    HOME --> PRICE
+    HOME --> BLOG
+    HOME --> ABOUT
+
+    FEAT --> F1[Analytics]
+    FEAT --> F2[Automation]
+```