show selling costs transparently in tooltip and label on result card

calc.js

@@ -68,6 +68,7 @@ function run_simulation(p) {
   cum_rent_arr.push(0);
   detail_arr.push({
     house_value:      Math.round(home_value),
+    selling_costs:    Math.round(selling_costs_0),
     mortgage_balance: Math.round(balance),
     buyer_portfolio:  Math.round(buyer_portfolio),
     yr_interest:      0,
@@ -143,6 +144,7 @@ function run_simulation(p) {
       cum_rent_arr.push(Math.round(cum_rent_cost));
       detail_arr.push({
         house_value:     Math.round(home_value),
+        selling_costs:   Math.round(selling_costs),
         mortgage_balance: Math.round(balance),
         buyer_portfolio: Math.round(buyer_portfolio),
         yr_interest:     Math.round(yr_interest),

index.html

@@ -232,6 +232,7 @@
           <div class="result-label">Nettovermögen Kauf</div>
           <div class="result-value" id="res_buyer_nw">—</div>
           <div class="result-sub" id="res_buy_cost">Gesamtausgaben: —</div>
+          <div class="result-sub" style="color:var(--text-hint)">inkl. Verkaufskosten</div>
         </div>
         <div class="result-card rent-card">
           <div class="result-label">Nettovermögen Miete</div>

ui.js

@@ -193,6 +193,7 @@ const build_table = (result) => {
     td_buy_nw.classList.add('has-tip');
     td_buy_nw.addEventListener('mouseenter', (e) => show_tooltip(e, [
       tip_row('Immobilienwert', d.house_value, '#f59e0b'),
+      tip_row('Verkaufskosten', -d.selling_costs, '#ef4444'),
       tip_row('ETF-Portfolio',  d.buyer_portfolio, '#f59e0b'),
       tip_row('Restschuld',    -d.mortgage_balance, '#ef4444'),
     ].join('<br>')));