fix(lint): fix all linting errors

- Check BindEnv return values in config.go
- Add bounds checks for int->int32/uint32 conversions to prevent overflow
- Remove unused test helper functions

internal/config/config.go

@@ -100,9 +100,15 @@ func LoadConfig(env string) (config.ConfigProvider, error) {
 	// e.g., DATABASE_DSN -> database.dsn, SERVER_PORT -> server.port
 	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	// Bind specific environment variables to config keys
-	v.BindEnv("database.dsn", "DATABASE_DSN")
-	v.BindEnv("registry.consul.address", "REGISTRY_CONSUL_ADDRESS")
-	v.BindEnv("registry.type", "REGISTRY_TYPE")
+	if err := v.BindEnv("database.dsn", "DATABASE_DSN"); err != nil {
+		return nil, fmt.Errorf("failed to bind DATABASE_DSN: %w", err)
+	}
+	if err := v.BindEnv("registry.consul.address", "REGISTRY_CONSUL_ADDRESS"); err != nil {
+		return nil, fmt.Errorf("failed to bind REGISTRY_CONSUL_ADDRESS: %w", err)
+	}
+	if err := v.BindEnv("registry.type", "REGISTRY_TYPE"); err != nil {
+		return nil, fmt.Errorf("failed to bind REGISTRY_TYPE: %w", err)
+	}
 
 	return NewViperConfig(v), nil
 }