hover tooltips on Übersicht table with breakdown details

calc.js

@@ -44,8 +44,12 @@ function run_simulation(p) {
   const renter_nw_arr = [];
   const cum_buy_arr = [];
   const cum_rent_arr = [];
+  const detail_arr = [];
   const labels = [];
 
+  // yearly accumulators (reset each year)
+  let yr_interest = 0, yr_principal = 0, yr_upkeep = 0;
+
   let breakeven_month = null;
 
   const invest_r_m = p.invest_return / 100 / 12;
@@ -65,7 +69,10 @@ function run_simulation(p) {
     // German context: no mortgage interest tax deduction for private buyers
     const total_buy_m = monthly_payment + prop_tax_m + maint_m + insurance_m;
 
-    cum_buy_cost += total_buy_m;
+    yr_interest   += interest_m;
+    yr_principal  += principal_m;
+    yr_upkeep     += prop_tax_m + maint_m + insurance_m;
+    cum_buy_cost  += total_buy_m;
 
     buyer_portfolio *= (1 + invest_r_m);
     const selling_costs = home_value * (p.closing_sell_pct / 100);
@@ -103,6 +110,14 @@ function run_simulation(p) {
       renter_nw_arr.push(Math.round(portfolio - tax_on_gains));
       cum_buy_arr.push(Math.round(cum_buy_cost));
       cum_rent_arr.push(Math.round(cum_rent_cost));
+      detail_arr.push({
+        house_value:     Math.round(home_value),
+        buyer_portfolio: Math.round(buyer_portfolio),
+        yr_interest:     Math.round(yr_interest),
+        yr_principal:    Math.round(yr_principal),
+        yr_upkeep:       Math.round(yr_upkeep),
+      });
+      yr_interest = 0; yr_principal = 0; yr_upkeep = 0;
     }
   }
 
@@ -116,6 +131,7 @@ function run_simulation(p) {
     renter_nw_arr,
     cum_buy_arr,
     cum_rent_arr,
+    detail_arr,
     monthly_payment: Math.round(monthly_payment),
     final_buyer_nw,
     final_renter_nw,