This commit splits out synchronization primitives from LibThreading into
LibSync. This is because LibThreading depends on LibCore, while LibCore
needs the synchronization primitives from LibThreading. This worked
while they were header only, but when I tried to add an implementation
file it ran into the circular dependency. To abstract away the pthread
implementation using cpp files is necessary so the synchronization
primitives were moved to a separate library.
Add the core infrastructure for the GTK frontend:
- EventLoopImplementationGtk: GLib main loop integration with
Core::EventLoop, timers, notifiers, and signal handling
- GObjectPtr RAII wrapper for GObject lifecycle management
- Application subclass with AdwApplication and D-Bus registration
- Minimal main.cpp entry point
The application starts and runs the event loop but does not yet
open any windows.
