chore: align forest AI development setup

backend/internal/config/config.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
@@ -45,5 +46,18 @@ func LoadFromDir(configDir string) (Config, error) {
 	if cfg.MaxUploadBytes <= 0 {
 		cfg.MaxUploadBytes = 32 << 20
 	}
+	if strings.TrimSpace(cfg.StorageDir) == "" {
+		return Config{}, fmt.Errorf("storage_dir must not be empty")
+	}
+	hasAllowedOrigin := false
+	for _, origin := range cfg.AllowedOrigins {
+		if strings.TrimSpace(origin) != "" {
+			hasAllowedOrigin = true
+			break
+		}
+	}
+	if !hasAllowedOrigin {
+		return Config{}, fmt.Errorf("allowed_origins must include at least one origin")
+	}
 	return cfg, nil
 }