Add targeted startup logging

[danielchalmers]

Adds lightweight Microsoft.Extensions.Logging timing around the startup and first-home-load paths so issue #91 has concrete launch measurements to work from.

The Android launch logs showed that the splash delay is currently dominated by startup database work, especially the pending migration check and category seeding. These targeted logs expose that without introducing a new tracing abstraction or changing runtime behavior.

Changes include:

• startup phase timing in MauiProgram.CreateMauiApp
• database preparation, category seeding, and debug day seeding timing in AppDbSeeder
• home initialization and day-load timing in Index.razor
• first Blazor layout render logging in MainLayout.razor