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/insertr.yaml

@@ -0,0 +1,58 @@
+# Insertr Configuration for Devigo Demo Site
+# Norwegian consulting website demonstrating production use case
+
+# Global settings
+dev_mode: true           # Development mode for demos
+
+# Database configuration  
+database:
+  path: "./insertr.db"   # Shared database with main config
+
+# Demo-specific configuration
+demo:
+  site_id: "devigo-web"  # Unique site ID for Devigo demo (matches server config)
+  inject_demo_gate: true # Auto-inject demo gate if no gates exist
+  mock_auth: true        # Use mock authentication for demos
+  api_endpoint: "http://localhost:8080/api/content"
+  # All sites served through unified server at localhost:8080/sites/devigo-web/
+
+# CLI enhancement configuration
+cli:
+  site_id: "devigo-web"  # Site ID for this demo (matches server config)
+  output: "./demos/devigo-web_enhanced" # Output directory for enhanced files
+  inject_demo_gate: true # Inject demo gate in development mode
+
+# Authentication configuration (for demo)
+auth:
+  provider: "mock"       # Mock auth for demos
+
+# Site-specific metadata
+site:
+  name: "Devigo - Digital Transformasjon"
+  description: "Norwegian consulting website showcasing digital transformation services"
+  language: "no"         # Norwegian language
+  url: "https://devigo.no"
+  type: "consulting"     # Site category
+  
+# Content types and examples for this demo
+content_examples:
+  - type: "text"
+    description: "Company name, service titles, contact information"
+    elements: ["h1", "h2", "h3", "span.brand-name"]
+    
+  - type: "markdown"
+    description: "Service descriptions, testimonials, company info"
+    elements: ["p", "blockquote", ".hero-subtitle"]
+    
+  - type: "link"
+    description: "Navigation links, call-to-action buttons"
+    elements: ["a.btn", "nav a"]
+
+# Features demonstrated in this demo
+features:
+  - norwegian_content: true
+  - consulting_services: true
+  - testimonials: true
+  - contact_forms: true
+  - responsive_design: true
+  - production_ready: true