donation item, shop soft open

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

shared/interfaces/Catcrafts.Shared-Model.cppm

@@ -200,6 +200,13 @@ export struct Product {
     // gap, price swing). In both closed states the page stays up, the buy
     // form does not, and the checkout POST is refused server-side.
     std::string status;
+    // A donation rather than goods: the buyer names the amount, nothing ships,
+    // and no VAT is charged (a gift with nothing supplied in return is not a
+    // taxable supply). This flag is what routes a checkout POST through the
+    // donation validator instead of the address-and-shipping one, so setting
+    // it on a priced product would let orders skip shipping — it belongs on
+    // exactly one kind of catalogue entry.
+    bool donation = false;
     // The EU consumer price, VAT-inclusive, in cents. With variants present
     // this is the FROM price (cheapest variant) and is kept in sync by the
     // loader; without variants it is simply the price.
@@ -226,7 +233,11 @@ export struct Product {
     std::string safetyNote;
     std::vector<Spec> specs;
 
-    bool Buyable() const { return status == "available" && priceInclMinor > 0; }
+    // A donation has no fixed price by definition, so the price check applies
+    // only to goods — where a zero price is a content bug that must not sell.
+    bool Buyable() const {
+        return status == "available" && (donation || priceInclMinor > 0);
+    }
     bool ComingSoon() const { return status == "coming-soon"; }
 
     // nullptr for a colour we never listed — the checkout rejects rather than
@@ -381,6 +392,10 @@ export struct OrderView {
     std::int64_t shippingMinor = 0;
     std::int64_t totalMinor = 0;
     bool vatIncluded = false;
+    // A donation order: one amount, nothing ships, no VAT, no invoice. The
+    // renderer folds the money table to a single row and swaps the paid-state
+    // copy from "your device ships" to a thank-you.
+    bool donation = false;
     // Present only for an awaiting order on a rail without a hosted checkout;
     // the page then renders instructions instead of a "resume payment" button.
     std::optional<OrderCryptoPay> cryptoPay;