fix: use real-time balances for dashboard net worth calculation (#200)

* fix: use real-time balances for dashboard net worth calculation

The dashboard was using only Account.CurrentBalance (the static initial
balance) to calculate TotalBalance, NetWorth, TotalAssets, and
TotalLiabilities. This ignored all transactions, causing the dashboard
to show incorrect values compared to the accounts page.

Now uses GetAccountBalancesAsync() which correctly computes
InitialBalance + Sum(Transactions) — the same method the accounts page
already uses.

Fixes #199

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* refactor: calculate balance, assets, liabilities in a single pass

Refactored the three separate LINQ iterations over userAccounts into a
single GroupBy pass using a dictionary, as suggested by code review.
This improves performance and consolidates the related calculations.

---------

Co-authored-by: Rodrigo Leote <rodrigol@leapthought.co.nz>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

src/Core/MyMascada.Application/Features/Reports/Queries/GetDashboardSummaryQuery.cs

@@ -31,16 +31,21 @@ public async Task<DashboardSummaryDto> Handle(GetDashboardSummaryQuery request,
         // Get user's accounts
         var userAccounts = (await _accountRepository.GetByUserIdAsync(request.UserId)).ToList();
 
-        // Calculate total balance from accounts
-        var totalBalance = userAccounts.Sum(a => a.CurrentBalance);
-
-        // Net worth breakdown: CreditCard(3) + Loan(5) = liabilities, rest = assets
-        var totalAssets = userAccounts
-            .Where(a => a.Type != AccountType.CreditCard && a.Type != AccountType.Loan)
-            .Sum(a => a.CurrentBalance);
-        var totalLiabilities = Math.Abs(userAccounts
-            .Where(a => a.Type == AccountType.CreditCard || a.Type == AccountType.Loan)
-            .Sum(a => a.CurrentBalance));
+        // Get real-time balances (initial balance + transaction sums)
+        var accountBalances = await _transactionRepository.GetAccountBalancesAsync(request.UserId);
+
+        decimal GetBalance(Domain.Entities.Account a) => accountBalances.GetValueOrDefault(a.Id, a.CurrentBalance);
+
+        // Calculate total balance, assets, and liabilities in one pass
+        var balanceByType = userAccounts
+            .GroupBy(a => a.Type == AccountType.CreditCard || a.Type == AccountType.Loan) // true: liabilities, false: assets
+            .ToDictionary(g => g.Key, g => g.Sum(GetBalance));
+
+        var totalAssets = balanceByType.GetValueOrDefault(false, 0m);
+        var totalLiabilitiesRaw = balanceByType.GetValueOrDefault(true, 0m);
+
+        var totalBalance = totalAssets + totalLiabilitiesRaw;
+        var totalLiabilities = Math.Abs(totalLiabilitiesRaw);
         var netWorth = totalAssets - totalLiabilities;
 
         // Get current month boundaries