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/url-structure.md

@@ -0,0 +1,46 @@
+# URL Structure
+
+## Design Principles
+
+1. **Readable by humans** — `/features/analytics` not `/f/a123`
+2. **Hyphens, not underscores** — `/blog/seo-guide` not `/blog/seo_guide`
+3. **Reflect the hierarchy** — URL path should match site structure
+4. **Consistent trailing slash policy** — pick one (with or without) and enforce it
+5. **Lowercase always** — `/About` should redirect to `/about`
+6. **Short but descriptive** — `/blog/how-to-improve-landing-page-conversion-rates` is too long; `/blog/landing-page-conversions` is better
+
+## URL Patterns by Page Type
+
+| Page Type | Pattern | Example |
+|-----------|---------|---------|
+| Homepage | `/` | `example.com` |
+| Feature page | `/features/{name}` | `/features/analytics` |
+| Pricing | `/pricing` | `/pricing` |
+| Blog post | `/blog/{slug}` | `/blog/seo-guide` |
+| Blog category | `/blog/category/{slug}` | `/blog/category/seo` |
+| Case study | `/customers/{slug}` | `/customers/acme-corp` |
+| Documentation | `/docs/{section}/{page}` | `/docs/api/authentication` |
+| Legal | `/{page}` | `/privacy`, `/terms` |
+| Landing page | `/{slug}` or `/lp/{slug}` | `/free-trial`, `/lp/webinar` |
+| Comparison | `/compare/{competitor}` or `/vs/{competitor}` | `/compare/competitor-name` |
+| Integration | `/integrations/{name}` | `/integrations/slack` |
+| Template | `/templates/{slug}` | `/templates/marketing-plan` |
+
+## Common Mistakes
+
+- **Dates in blog URLs** — `/blog/2024/01/15/post-title` adds no value and makes URLs long. Use `/blog/post-title`.
+- **Over-nesting** — `/products/category/subcategory/item/detail` is too deep. Flatten where possible.
+- **Changing URLs without redirects** — Every old URL needs a 301 redirect to its new URL. Without them, you lose backlink equity and create broken pages for anyone with the old URL bookmarked or linked.
+- **IDs in URLs** — `/product/12345` is not human-readable. Use slugs.
+- **Query parameters for content** — `/blog?id=123` should be `/blog/post-title`.
+- **Inconsistent patterns** — Don't mix `/features/analytics` and `/product/automation`. Pick one parent.
+
+## Breadcrumb-URL Alignment
+
+The breadcrumb trail should mirror the URL path:
+
+| URL | Breadcrumb |
+|-----|-----------|
+| `/features/analytics` | Home > Features > Analytics |
+| `/blog/seo-guide` | Home > Blog > SEO Guide |
+| `/docs/api/auth` | Home > Docs > API > Authentication |