Refactor configuration system with centralized type-safe config package

- Create internal/config package with unified config structs and validation
- Abstract viper dependency behind config.Loader interface for better testability
- Replace manual config parsing and type assertions with type-safe loading
- Consolidate AuthConfig, SiteConfig, and DiscoveryConfig into single package
- Add comprehensive validation with clear error messages
- Remove ~200 lines of duplicate config handling code
- Maintain backward compatibility with existing config files

cmd/enhance.go

@@ -8,7 +8,6 @@ import (
 	"strings"
 
 	"github.com/spf13/cobra"
-	"github.com/spf13/viper"
 
 	"github.com/insertr/insertr/internal/content"
 	"github.com/insertr/insertr/internal/db"
@@ -34,9 +33,6 @@ var (
 
 func init() {
 	enhanceCmd.Flags().StringVarP(&outputDir, "output", "o", "./dist", "Output directory for enhanced files")
-
-	// Bind flags to viper
-	viper.BindPFlag("cli.output", enhanceCmd.Flags().Lookup("output"))
 }
 
 func runEnhance(cmd *cobra.Command, args []string) {
@@ -59,20 +55,26 @@ func runEnhance(cmd *cobra.Command, args []string) {
 		}
 	}
 
-	// Get configuration values
-	dbPath := viper.GetString("database.path")
-	apiURL := viper.GetString("api.url")
-	apiKey := viper.GetString("api.key")
-	siteID := viper.GetString("cli.site_id")
-	outputDir := viper.GetString("cli.output")
+	// Load configuration
+	cfg, err := loadConfig()
+	if err != nil {
+		log.Fatalf("Failed to load configuration: %v", err)
+	}
+
+	// Override with flags if provided
+	if outputDir != "" {
+		// No output config in main config, use the flag value directly
+	} else {
+		outputDir = "./dist" // default
+	}
 
 	// Auto-derive site_id for demo paths or validate for production
 	if strings.Contains(inputPath, "/demos/") || strings.Contains(inputPath, "./demos/") {
 		// Auto-derive site_id from demo path
-		siteID = content.DeriveOrValidateSiteID(inputPath, siteID)
+		cfg.CLI.SiteID = content.DeriveOrValidateSiteID(inputPath, cfg.CLI.SiteID)
 	} else {
 		// Validate site_id for non-demo paths
-		if siteID == "" || siteID == "demo" {
+		if cfg.CLI.SiteID == "" || cfg.CLI.SiteID == "demo" {
 			log.Fatalf(`❌ site_id must be explicitly configured for non-demo sites.
 
 💡 Examples:
@@ -92,12 +94,12 @@ func runEnhance(cmd *cobra.Command, args []string) {
 
 	// Create content client
 	var client engine.ContentClient
-	if apiURL != "" {
-		fmt.Printf("🌐 Using content API: %s\n", apiURL)
-		client = content.NewHTTPClient(apiURL, apiKey)
-	} else if dbPath != "" {
-		fmt.Printf("🗄️ Using database: %s\n", dbPath)
-		database, err := db.NewDatabase(dbPath)
+	if cfg.API.URL != "" {
+		fmt.Printf("🌐 Using content API: %s\n", cfg.API.URL)
+		client = content.NewHTTPClient(cfg.API.URL, cfg.API.Key)
+	} else if cfg.Database.Path != "" {
+		fmt.Printf("🗄️ Using database: %s\n", cfg.Database.Path)
+		database, err := db.NewDatabase(cfg.Database.Path)
 		if err != nil {
 			log.Fatalf("Failed to initialize database: %v", err)
 		}
@@ -121,41 +123,24 @@ func runEnhance(cmd *cobra.Command, args []string) {
 	}
 
 	// Override with site-specific discovery config if available
-	if siteConfigs := viper.Get("server.sites"); siteConfigs != nil {
-		if configs, ok := siteConfigs.([]interface{}); ok {
-			for _, configInterface := range configs {
-				if configMap, ok := configInterface.(map[string]interface{}); ok {
-					if configSiteID, ok := configMap["site_id"].(string); ok && configSiteID == siteID {
-						// Found matching site config, load discovery settings
-						if discoveryMap, ok := configMap["discovery"].(map[string]interface{}); ok {
-							if enabled, ok := discoveryMap["enabled"].(bool); ok {
-								enhancementConfig.Discovery.Enabled = enabled
-								fmt.Printf("🔧 Site '%s': discovery.enabled=%v\n", siteID, enabled)
-							}
-							if aggressive, ok := discoveryMap["aggressive"].(bool); ok {
-								enhancementConfig.Discovery.Aggressive = aggressive
-							}
-							if containers, ok := discoveryMap["containers"].(bool); ok {
-								enhancementConfig.Discovery.Containers = containers
-							}
-							if individual, ok := discoveryMap["individual"].(bool); ok {
-								enhancementConfig.Discovery.Individual = individual
-							}
-						}
-						break
-					}
-				}
-			}
+	for _, site := range cfg.Server.Sites {
+		if site.SiteID == cfg.CLI.SiteID && site.Discovery != nil {
+			enhancementConfig.Discovery.Enabled = site.Discovery.Enabled
+			enhancementConfig.Discovery.Aggressive = site.Discovery.Aggressive
+			enhancementConfig.Discovery.Containers = site.Discovery.Containers
+			enhancementConfig.Discovery.Individual = site.Discovery.Individual
+			fmt.Printf("🔧 Site '%s': discovery.enabled=%v\n", cfg.CLI.SiteID, site.Discovery.Enabled)
+			break
 		}
 	}
 
 	// Create enhancer with loaded configuration
-	enhancer := content.NewEnhancer(client, siteID, enhancementConfig)
+	enhancer := content.NewEnhancer(client, cfg.CLI.SiteID, enhancementConfig)
 
 	fmt.Printf("🚀 Starting enhancement process...\n")
 	fmt.Printf("📁 Input: %s\n", inputPath)
 	fmt.Printf("📁 Output: %s\n", outputDir)
-	fmt.Printf("🏷️  Site ID: %s\n\n", siteID)
+	fmt.Printf("🏷️  Site ID: %s\n\n", cfg.CLI.SiteID)
 
 	// Enhance based on input type
 	if isFile {