donation item, shop soft open

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

server/implementations/Catcrafts.Server-Mail.cpp

@@ -75,6 +75,38 @@ std::string BuildOrderConfirmationEmail(const OrderRecord& o,
     // CR/LF would become an extra recipient, so the check repeats here.
     if (!Form::LooksLikeEmail(o.buyer.email)) return {};
 
+    // A donation's confirmation is a different message: a thank-you, no
+    // invoice attached (none exists), no dispatch promise (nothing ships).
+    // Single-part plain text — multipart with one part is just noise.
+    if (o.donation) {
+        std::string m;
+        m.reserve(1024);
+        m += std::format("From: {}\n", from);
+        m += std::format("To: {}\n", o.buyer.email);
+        m += std::format("Subject: Catcrafts donation {} received\n", o.reference);
+        m += std::format("Date: {}\n", dateRfc2822);
+        m += std::format("Message-ID: <{}@{}>\n", o.token, kSellerSite);
+        m += "MIME-Version: 1.0\n";
+        m += "Content-Type: text/plain; charset=utf-8\n";
+        m += "Content-Transfer-Encoding: 8bit\n\n";
+        m += std::format("Thank you — your donation {} of {} has arrived.\n\n",
+                         o.reference, Money::FormatEuro(o.totalMinor));
+        if (!o.paidVia.empty()) {
+            m += std::format("* Paid via: {}\n\n", o.paidVia);
+        }
+        m += "It funds the open-source work directly and will appear in the "
+             "running total on https://catcrafts.net/financials — as an "
+             "aggregate, never individually. No VAT applies to a donation and "
+             "no invoice is issued; this email and the donation page are the "
+             "receipt:\n\n";
+        m += std::format("  {}\n\n", orderUrl);
+        m += "Questions? Reply to this email.\n\n";
+        m += std::format("{} · {} · {}\n", kSellerName, kSellerStreet, kSellerCity);
+        m += std::format("KVK {} · VAT {} · https://{}\n", kSellerKvk, kSellerVat,
+                         kSellerSite);
+        return m;
+    }
+
     const std::string item = colorLabel.empty()
         ? std::string(productName)
         : std::format("{} — {}", productName, colorLabel);