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/navigation-design.md

@@ -0,0 +1,37 @@
+# Navigation Design
+
+## Navigation Types
+
+| Nav Type | Purpose | Placement |
+|----------|---------|-----------|
+| Header nav | Primary navigation, always visible | Top of every page |
+| Dropdown menus | Organize sub-pages under parent | Expands from header items |
+| Footer nav | Secondary links, legal, sitemap | Bottom of every page |
+| Sidebar nav | Section navigation (docs, blog) | Left side within a section |
+| Breadcrumbs | Show current location in hierarchy | Below header, above content |
+| Contextual links | Related content, next steps | Within page content |
+
+## Header Navigation Rules
+
+- **4-7 items max** in the primary nav (more causes decision paralysis)
+- **CTA button** goes rightmost (e.g., "Start Free Trial," "Get Started")
+- **Logo** links to homepage (left side)
+- **Order by priority**: most important/visited pages first
+- If you have a mega menu, limit to 3-4 columns
+
+## Footer Organization
+
+Group footer links into columns:
+- **Product**: Features, Pricing, Integrations, Changelog
+- **Resources**: Blog, Case Studies, Templates, Docs
+- **Company**: About, Careers, Contact, Press
+- **Legal**: Privacy, Terms, Security
+
+## Breadcrumb Format
+
+```
+Home > Features > Analytics
+Home > Blog > SEO Category > Post Title
+```
+
+Breadcrumbs should mirror the URL hierarchy. Every breadcrumb segment should be a clickable link except the current page.