GetCompletedValue() semantics: returns the highest confirmed completed value,
not the last Signal() target value. When Signal(5) -> Signal(3),
GetCompletedValue() should still return >= 5 since GPU already completed that.
- Remove IsSignaled() from RHIFence interface (semantic inconsistency)
- Remove Reset() from OpenGL implementation (no D3D12 counterpart)
- OpenGL Fence now uses single GLsync + CPU counters for timeline simulation
- OpenGL Fence Initialize() now accepts uint64_t initialValue (was bool)
- Add comprehensive timeline semantics tests for all backends:
- Signal increment/decrement scenarios
- Multiple signals
- Wait smaller than completed value
- GetCompletedValue stages verification
- Update documentation to reflect actual implementation
- Move old test files to new unit/integration structure
- Add OpenGL Test Fixture
- Update CMakeLists.txt for new layout
- Add OpenGL_Test_Restructuring_Plan.md
