feat: add payment tracking for orders

- Add payment method selection (PayPal/Bar) to order form
- Store payment_method and payment_status in database
- Add payment status badges in admin orders view
- Add "mark as paid" functionality for admins
- PayPal account configurable via PAYPAL_ACCOUNT env variable
- Frontend loads PayPal account dynamically from /wawi/config endpoint
- Update email notifications to include payment method

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

index.html

@@ -428,6 +428,22 @@
         <label style="grid-column: 1 / -1;">Notiz
           <textarea id="fNotiz" name="notiz" rows="3"></textarea>
         </label>
+        <div style="grid-column: 1 / -1; padding: 12px; background: #f0f9ff; border: 1px solid #bfdbfe; border-radius: 4px; margin-top: 8px;">
+          <strong>Zahlungsart wählen:</strong>
+          <div style="margin-top: 8px;">
+            <label style="display: flex; align-items: center; margin-bottom: 8px;">
+              <input type="radio" name="payment_method" value="paypal" checked style="margin-right: 8px;" />
+              <span><strong>PayPal (Familie & Freunde)</strong></span>
+            </label>
+            <div id="paypalInfo" style="margin-left: 28px; margin-bottom: 12px; font-size: 0.95em; color: #1e40af;">
+              Bitte sende den Betrag über PayPal an: <strong id="paypalAccount">–</strong>
+            </div>
+            <label style="display: flex; align-items: center;">
+              <input type="radio" name="payment_method" value="bar" style="margin-right: 8px;" />
+              <span><strong>Bar bei Abholung</strong></span>
+            </label>
+          </div>
+        </div>
       </div>
       <div class="form-actions">
         <button type="button" class="btn" id="orderCancel">Abbrechen</button>
@@ -568,6 +584,20 @@ const form = document.getElementById("orderForm");
 const setField = (id, v) => document.getElementById(id).value = v || "";
 const ORDER_KEY = "";
 
+// PayPal-Konto vom Backend laden
+fetch("/wawi/config")
+  .then(res => res.json())
+  .then(config => {
+    if (config.paypal_account) {
+      document.getElementById("paypalAccount").textContent = config.paypal_account;
+    } else {
+      document.getElementById("paypalAccount").textContent = "Nicht konfiguriert";
+    }
+  })
+  .catch(() => {
+    document.getElementById("paypalAccount").textContent = "Fehler beim Laden";
+  });
+
 document.addEventListener("click", (e) => {
   const imgBtn = e.target.closest(".thumb-btn");
   if (imgBtn) {