Phase 8: Polish and production readiness

- Add ErrorBoundary component wrapping the whole app
- Add ToastProvider with showError/showInfo; Income and Outgo pages use it for API errors
- Add LoadingSkeleton component with shimmer animation; Income and Outgo show it while loading
- Add confirm-on-delete dialogs for income and outgo rows
- Apply EF migrations automatically on startup via MigrateAsync()
- Add /healthz health check endpoint using DbContext check
- Add Microsoft.Extensions.Diagnostics.HealthChecks.EntityFrameworkCore package

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

src/Budget.Api/Program.cs

@@ -1,7 +1,9 @@
 using Budget.Api.Data;
 using Budget.Api.Services;
 using Microsoft.AspNetCore.Authentication.JwtBearer;
+using Microsoft.AspNetCore.Diagnostics.HealthChecks;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Diagnostics.HealthChecks;
 using Microsoft.IdentityModel.Tokens;
 
 var builder = WebApplication.CreateBuilder(args);
@@ -29,11 +31,20 @@ builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
     });
 
 builder.Services.AddAuthorization();
-builder.Services.AddScoped<Budget.Api.Services.BudgetAuthorizationService>();
+builder.Services.AddScoped<BudgetAuthorizationService>();
 builder.Services.AddControllers();
+builder.Services.AddHealthChecks()
+    .AddDbContextCheck<AppDbContext>();
 
 var app = builder.Build();
 
+// Apply EF migrations automatically on startup
+using (var scope = app.Services.CreateScope())
+{
+    var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
+    await db.Database.MigrateAsync();
+}
+
 app.UseDefaultFiles();
 app.UseStaticFiles();
 
@@ -43,6 +54,15 @@ app.UseAuthorization();
 app.UseMiddleware<KnownUserMiddleware>();
 
 app.MapControllers();
+app.MapHealthChecks("/healthz", new HealthCheckOptions
+{
+    ResultStatusCodes =
+    {
+        [HealthStatus.Healthy] = StatusCodes.Status200OK,
+        [HealthStatus.Degraded] = StatusCodes.Status200OK,
+        [HealthStatus.Unhealthy] = StatusCodes.Status503ServiceUnavailable,
+    }
+});
 
 app.MapFallbackToFile("index.html");