feat: wire up Program.cs, DI extensions, Serilog, and appsettings

- ServiceCollectionExtensions in DAL.EF: AddNotificationDataAccess (DbContext, UoW, repositories)
- ServiceCollectionExtensions in Services: AddNotificationServices (MediatR + TransactionBehavior)
- Api/Program.cs: Serilog, OpenAPI, controllers, DI wiring
- Worker/Program.cs: Serilog, DI wiring
- appsettings.json: Serilog config with Console + Seq sinks, connection string
- appsettings.Development.json: Debug log level overrides

Ref: IT-628

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

HrynCo.NotificationService.Api/Program.cs

@@ -1,41 +1,26 @@
+using HrynCo.NotificationService.DAL.EF;
+using HrynCo.NotificationService.Services;
+using Serilog;
+
 var builder = WebApplication.CreateBuilder(args);
 
-// Add services to the container.
-// Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
+builder.Host.UseSerilog((context, lc) =>
+    lc.ReadFrom.Configuration(context.Configuration));
+
 builder.Services.AddOpenApi();
+builder.Services.AddControllers();
+
+string connectionString = builder.Configuration.GetConnectionString("Default")
+    ?? throw new InvalidOperationException("Connection string 'Default' is not configured.");
+
+builder.Services.AddNotificationDataAccess(connectionString);
+builder.Services.AddNotificationServices();
 
 var app = builder.Build();
 
-// Configure the HTTP request pipeline.
 if (app.Environment.IsDevelopment())
-{
     app.MapOpenApi();
-}
 
 app.UseHttpsRedirection();
-
-var summaries = new[]
-{
-    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
-};
-
-app.MapGet("/weatherforecast", () =>
-{
-    var forecast =  Enumerable.Range(1, 5).Select(index =>
-        new WeatherForecast
-        (
-            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
-            Random.Shared.Next(-20, 55),
-            summaries[Random.Shared.Next(summaries.Length)]
-        ))
-        .ToArray();
-    return forecast;
-})
-.WithName("GetWeatherForecast");
-
-app.Run();
-
-record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
-{
-    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
-}
+app.MapControllers();
+app.Run();