config: unify configuration with multi-site support

- Remove mock_content setting (working database loop makes it unnecessary)
- Change server.dev_mode to global dev_mode setting for consistency
- Update CLI to use cli.site_id and cli.output for scoped configuration
- Implement database client for CLI enhance command (complete static site loop)
- Update justfile to use INSERTR_DATABASE_PATH environment variable
- Enable multi-site architecture: server is site-agnostic, CLI is site-specific
- Unified insertr.yaml now supports both server and CLI with minimal config

cmd/serve.go

@@ -35,14 +35,14 @@ func init() {
 
 	// Bind flags to viper
 	viper.BindPFlag("server.port", serveCmd.Flags().Lookup("port"))
-	viper.BindPFlag("server.dev_mode", serveCmd.Flags().Lookup("dev-mode"))
+	viper.BindPFlag("dev_mode", serveCmd.Flags().Lookup("dev-mode"))
 }
 
 func runServe(cmd *cobra.Command, args []string) {
 	// Get configuration values
 	port := viper.GetInt("server.port")
 	dbPath := viper.GetString("database.path")
-	devMode := viper.GetBool("server.dev_mode")
+	devMode := viper.GetBool("dev_mode")
 
 	// Initialize database
 	database, err := db.NewDatabase(dbPath)