TaskyPad 1.0.4

Enhance notifications and task postponement support

Added support for displaying a custom app icon (`logo.ico`) in
Windows toast notifications and improved notification content
layout with new postpone buttons (1, 5, 10 minutes). Updated
`TaskService` to handle postpone actions and ensure robust UI
updates when `MainWindow` is null.

Modified `TaskyPad.csproj` to include `logo.ico`, remove unused
resources, increment assembly version to 1.0.4, and update the
target framework to `net9.0-windows10.0.19041.0`.