Initial commit of Descrybe v2 without local scratch artifacts.

Drop one-shot tmp/axe scripts and agent i18n scratch so the Gitea tree is deployable.

apps/api/internal/billing/client_errors.go

@@ -0,0 +1,36 @@
+package billing
+
+import "errors"
+
+var (
+	ErrPlanNameRequired = errors.New("name required")
+	ErrPlanNotFound     = errors.New("plan not found")
+	ErrAmountRequired   = errors.New("amount required")
+	ErrStripeNoCustomer = errors.New("no stripe customer for this company — complete a checkout first")
+)
+
+// ClientError reports whether err is a known client-facing billing/Stripe error.
+func ClientError(err error) (msg string, ok bool) {
+	switch {
+	case err == nil:
+		return "", false
+	case errors.Is(err, ErrPlanNameRequired),
+		errors.Is(err, ErrPlanNotFound),
+		errors.Is(err, ErrAmountRequired),
+		errors.Is(err, ErrStripeNotConfigured),
+		errors.Is(err, ErrStripePlanUnsupported),
+		errors.Is(err, ErrStripePriceMissing),
+		errors.Is(err, ErrStripeNoCustomer),
+		errors.Is(err, ErrInsufficientCredits),
+		errors.Is(err, ErrProductLimitExceeded),
+		errors.Is(err, ErrAIRequiresUpgrade),
+		errors.Is(err, ErrEPRELRequiresUpgrade),
+		errors.Is(err, ErrUnknownFeatureKey),
+		errors.Is(err, ErrUnknownFeatureSection),
+		errors.Is(err, ErrInvalidFeatureGates),
+		errors.Is(err, ErrFeatureDisabled):
+		return err.Error(), true
+	default:
+		return "", false
+	}
+}