Config: Set default culture to en-US for currency formatting

Ensures consistent $ currency display regardless of server locale

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

MoneyMap/Program.cs

@@ -1,7 +1,13 @@
+using System.Globalization;
 using Microsoft.EntityFrameworkCore;
 using MoneyMap.Data;
 using MoneyMap.Services;
 
+// Set default culture to en-US for currency formatting ($)
+var culture = new CultureInfo("en-US");
+CultureInfo.DefaultThreadCurrentCulture = culture;
+CultureInfo.DefaultThreadCurrentUICulture = culture;
+
 var builder = WebApplication.CreateBuilder(args);
 
 builder.Services.AddRazorPages();