Migrate to Chi router and add Norwegian Devigo demo

Major improvements:
- Replace Gorilla Mux with Chi v5 router for better performance and cleaner code
- Fix CSS/JS MIME type issues that prevented proper asset loading
- Add built-in CORS middleware replacing manual OPTIONS handlers
- Simplify routing with nested route syntax
- Update URL parameter extraction from mux.Vars to chi.URLParam

New Devigo demo:
- Add production Norwegian sales training website (devigo.no)
- Real-world Hugo-generated content with TailwindCSS
- 39 insertr-enhanced elements for comprehensive CMS testing
- Demonstrates international language support and B2B use cases
- Fixed asset paths for localhost serving compatibility

Technical benefits:
- Automatic MIME type detection for static files
- Reduced code complexity with built-in middleware
- Better performance with lighter dependency stack
- Production-ready CORS handling

demos/devigo-web/assets/images/org-icon.svg

@@ -0,0 +1,8 @@
+<svg width="30" height="30" viewBox="0 0 30 30" fill="none" xmlns="http://www.w3.org/2000/svg">
+  <circle cx="15" cy="8" r="3" fill="white"/>
+  <circle cx="8" cy="20" r="2.5" fill="white"/>
+  <circle cx="22" cy="20" r="2.5" fill="white"/>
+  <path d="M15 12C12.2 12 10 14.2 10 17V18H20V17C20 14.2 17.8 12 15 12Z" fill="white"/>
+  <path d="M8 24C6.3 24 5 22.7 5 21V20.5C5 19.1 6.1 18 7.5 18H8.5C9.9 18 11 19.1 11 20.5V21C11 22.7 9.7 24 8 24Z" fill="white"/>
+  <path d="M22 24C20.3 24 19 22.7 19 21V20.5C19 19.1 20.1 18 21.5 18H22.5C23.9 18 25 19.1 25 20.5V21C25 22.7 23.7 24 22 24Z" fill="white"/>
+</svg>