fix: disable auto-enhancement in development mode to prevent live-reload loops

- Add dev_mode parameter to SiteManager constructor
- Modify IsAutoEnhanceEnabled() to return false when dev_mode is true
- Update serve.go to pass dev_mode flag to SiteManager
- Add ForceEnhanceEnabled() method for testing production behavior in development
- Update documentation to explain development vs production mode behavior

This fixes the development workflow where content updates would trigger
file modifications that caused unwanted page reloads in live-server.

Development mode: Content saved to database only, editor loads dynamically
Production mode: Content saved + files enhanced for immediate static deployment

cmd/serve.go

@@ -73,7 +73,7 @@ func runServe(cmd *cobra.Command, args []string) {
 	contentClient := content.NewDatabaseClient(database)
 
 	// Initialize site manager
-	siteManager := content.NewSiteManager(contentClient, "./insertr-backups")
+	siteManager := content.NewSiteManager(contentClient, "./insertr-backups", devMode)
 
 	// Load sites from configuration
 	if siteConfigs := viper.Get("server.sites"); siteConfigs != nil {