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

cmd/serve.go

@@ -8,7 +8,9 @@ import (
 	"os/signal"
 	"syscall"
 
-	"github.com/gorilla/mux"
+	"github.com/go-chi/chi/v5"
+	"github.com/go-chi/chi/v5/middleware"
+	"github.com/go-chi/cors"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 
@@ -120,55 +122,54 @@ func runServe(cmd *cobra.Command, args []string) {
 	contentHandler := api.NewContentHandler(database, authService)
 	contentHandler.SetSiteManager(siteManager)
 
-	// Setup router
-	router := mux.NewRouter()
+	// Setup Chi router
+	router := chi.NewRouter()
 
-	// Add middleware
-	router.Use(api.CORSMiddleware)
-	router.Use(api.LoggingMiddleware)
+	// Add Chi middleware
+	router.Use(middleware.Logger)
+	router.Use(middleware.Recoverer)
+	router.Use(cors.Handler(cors.Options{
+		AllowedOrigins:   []string{"*"}, // In dev mode, allow all origins
+		AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
+		AllowedHeaders:   []string{"*"},
+		ExposedHeaders:   []string{"Link"},
+		AllowCredentials: true,
+		MaxAge:           300, // Maximum value not ignored by any of major browsers
+	}))
 	router.Use(api.ContentTypeMiddleware)
 
 	// Health check endpoint
-	router.HandleFunc("/health", api.HealthMiddleware())
-
-	// API routes
-	apiRouter := router.PathPrefix("/api").Subrouter()
-
-	// Content endpoints
-	contentRouter := apiRouter.PathPrefix("/content").Subrouter()
-	contentRouter.HandleFunc("/bulk", contentHandler.GetBulkContent).Methods("GET")
-	contentRouter.HandleFunc("/{id}", contentHandler.GetContent).Methods("GET")
-
-	contentRouter.HandleFunc("", contentHandler.GetAllContent).Methods("GET")
-	contentRouter.HandleFunc("", contentHandler.CreateContent).Methods("POST")
-
-	// Version control endpoints
-	contentRouter.HandleFunc("/{id}/versions", contentHandler.GetContentVersions).Methods("GET")
-	contentRouter.HandleFunc("/{id}/rollback", contentHandler.RollbackContent).Methods("POST")
-
-	// Site enhancement endpoint
-	apiRouter.HandleFunc("/enhance", contentHandler.EnhanceSite).Methods("POST")
+	router.Get("/health", api.HealthMiddleware())
 
 	// Static library serving (for demo sites)
-	router.HandleFunc("/insertr.js", contentHandler.ServeInsertrJS).Methods("GET")
+	router.Get("/insertr.js", contentHandler.ServeInsertrJS)
+
+	// API routes
+	router.Route("/api", func(apiRouter chi.Router) {
+		// Site enhancement endpoint
+		apiRouter.Post("/enhance", contentHandler.EnhanceSite)
+
+		// Content endpoints
+		apiRouter.Route("/content", func(contentRouter chi.Router) {
+			contentRouter.Get("/bulk", contentHandler.GetBulkContent)
+			contentRouter.Get("/{id}", contentHandler.GetContent)
+			contentRouter.Get("/", contentHandler.GetAllContent)
+			contentRouter.Post("/", contentHandler.CreateContent)
+
+			// Version control endpoints
+			contentRouter.Get("/{id}/versions", contentHandler.GetContentVersions)
+			contentRouter.Post("/{id}/rollback", contentHandler.RollbackContent)
+		})
+	})
 
 	// Static site serving - serve registered sites at /sites/{site_id}
-	siteRouter := router.PathPrefix("/sites").Subrouter()
+	// This fixes the MIME type issues with Chi's FileServer
 	for siteID, siteConfig := range siteManager.GetAllSites() {
 		log.Printf("📁 Serving site %s from %s at /sites/%s/", siteID, siteConfig.Path, siteID)
-		siteRouter.PathPrefix("/" + siteID + "/").Handler(
-			http.StripPrefix("/sites/"+siteID+"/",
-				http.FileServer(http.Dir(siteConfig.Path))))
+		fileServer := http.FileServer(http.Dir(siteConfig.Path))
+		router.Handle("/sites/"+siteID+"/*", http.StripPrefix("/sites/"+siteID+"/", fileServer))
 	}
 
-	// Handle CORS preflight requests explicitly
-	contentRouter.HandleFunc("/{id}", api.CORSPreflightHandler).Methods("OPTIONS")
-	contentRouter.HandleFunc("", api.CORSPreflightHandler).Methods("OPTIONS")
-	contentRouter.HandleFunc("/bulk", api.CORSPreflightHandler).Methods("OPTIONS")
-	contentRouter.HandleFunc("/{id}/versions", api.CORSPreflightHandler).Methods("OPTIONS")
-	contentRouter.HandleFunc("/{id}/rollback", api.CORSPreflightHandler).Methods("OPTIONS")
-	apiRouter.HandleFunc("/enhance", api.CORSPreflightHandler).Methods("OPTIONS")
-
 	// Start server
 	addr := fmt.Sprintf(":%d", port)
 	mode := "production"