Add a public EventLoop class

[akreuzkamp]

Refactors the eventloop functionality of CoreApplication into its own EventLoop class. This EventLoop class can be used to execute event loops on worker threads.

Renames CoreApplication::eventLoop() to
CoreApplication::platformEventLoop() and make
CoreApplication::eventLoop() return a pointer to the new EventLoop type.

[Copilot]

Pull Request Overview

This PR refactors the event loop functionality from CoreApplication into a new standalone EventLoop class. This allows event loops to be created and executed on worker threads, enabling better thread-based event processing.

• Extracts event loop functionality from CoreApplication into a new public EventLoop class
• Renames CoreApplication::eventLoop() to platformEventLoop() and makes eventLoop() return the new EventLoop type
• Updates all references to use the appropriate event loop interface

Reviewed Changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
tests/auto/gui/gui_application/tst_gui_application.cpp	New test file for GuiApplication that validates EventLoop usage on worker threads
tests/auto/gui/gui_application/CMakeLists.txt	CMake configuration for the new GuiApplication tests
tests/auto/gui/CMakeLists.txt	Adds gui_application subdirectory to test build
tests/auto/foundation/object/tst_object.cpp	Updated tests to include worker thread EventLoop scenarios
tests/auto/foundation/core_application/tst_core_application.cpp	Refactored tests to use new EventLoop API and added worker thread test cases
tests/auto/foundation/common/event_mockups.h	Extracted shared test event classes into common header
src/KDGui/platform/linux/wayland/linux_wayland_platform_integration.cpp	Moved Wayland initialization logic to constructor and removed event loop initialization
src/KDGui/platform/linux/wayland/linux_wayland_platform_event_loop.cpp	Moved file descriptor registration to constructor
src/KDFoundation/timer.cpp	Updated to use EventLoop::instance() instead of CoreApplication event loop
src/KDFoundation/platform/win32/win32_platform_timer.cpp	Updated platform timer to use EventLoop::instance()
src/KDFoundation/platform/macos/macos_platform_timer.mm	Updated platform timer to use EventLoop::instance()
src/KDFoundation/platform/abstract_platform_integration.h	Added documentation warnings about initialization timing
src/KDFoundation/object.cpp	Updated to use EventLoop for deferred deletion
src/KDFoundation/file_descriptor_notifier.cpp	Updated to use current thread's EventLoop instead of CoreApplication
src/KDFoundation/event_receiver.cpp	Enhanced to clear events from both thread-local and main event loops
src/KDFoundation/event_loop.h	New EventLoop class header
src/KDFoundation/event_loop.cpp	New EventLoop class implementation
src/KDFoundation/core_application.h	Refactored to use EventLoop member instead of direct platform event loop
src/KDFoundation/core_application.cpp	Simplified implementation by delegating event loop functionality
src/KDFoundation/CMakeLists.txt	Added event_loop.cpp and event_loop.h to build

[Copilot]

[nitpick] The assertion message mentions that nested event loops are not supported, but the actual check only prevents multiple event loops per thread. Consider clarifying the message to match the actual restriction being enforced.

Suggested change

	assert(s_eventLoopInstance == nullptr && "Cannot have more than one event loop per thread. Nested event loops are not supported.");
	assert(s_eventLoopInstance == nullptr && "Cannot have more than one event loop per thread.");

[MiKom]

Looks good but we need to fix some things before it can land.

I also advise doing interactive rebase and squashing the pre-commit commits.

[MiKom]

Approved. I added some cppcheck fixes, removed one stale commented-out line in tests and changed one word in test description. I also squashed the pre-commit commits.