[Task] Add deterministic FlyCamera and controller coverage

[JeanPhilippeKernel]

Type

• Bug
• Feature
• Refactor / cleanup
• Task / chore

Overview

The FlyCamera redesign has no dedicated automated test coverage. Its state transitions, camera math, controller mapping, and input reset behavior should be verified without needing a Vulkan device.

Context

The current rendering suite validates render-graph and PSO behavior, but no FlyCamera test source exists. The implementation includes math and state-machine behavior that can be covered by CPU-only tests.

Related: #780, #781, #782, and ZEngine/docs/future-plan/fly-camera-redesign.md.

What needs to be done

1. Add a FlyCamera test fixture with deterministic camera settings and delta time.
2. Cover free-flight movement, diagonal normalization, speed scaling, smoothing, and pitch/yaw limits.
3. Cover pan, orbit, scroll zoom, focus animation, bookmarks, and viewport ray unprojection.
4. Cover viewport resize/aspect updates and zero-extent handling.
5. Add controller tests for Idle, Hover, Fly, cursor release, and PauseEventProcessing reset behavior.
6. Provide an InputManager fixture or narrow test seam so action mapping can be tested without GLFW/Vulkan.

Resources

• ZEngine/ZEngine/Rendering/Cameras/FlyCamera.h
• ZEngine/ZEngine/Controllers/FlyCameraController.h
• ZEngine/ZEngine/Input/InputManager.h
• ZEngine/tests/Rendering/RenderGraphTest.cpp for existing test conventions

Testing

• Build: cmake --build --preset Darwin_arm64_Debug --target ZEngineTests --parallel 1
• Run: ./Result.Darwin.arm64.Debug/ZEngine/tests/Debug/ZEngineTests --gtest_filter='FlyCamera*:FlyCameraController'
• Run the full suite before merge.

Acceptance criteria

• CPU-only tests cover camera math and all FlyCamera states.
• Controller input/state transitions are covered without a Vulkan fixture.
• Regressions from [Bug] Synchronize FlyCamera projection with docked viewport extent #780, [Feature] Replace placeholder FlyCamera raycast with a scene query #781, and [Bug] Harden FlyCamera input ownership, focus, and cursor capture #782 have targeted tests.
• Test names describe the user-visible behavior being protected.
• Builds without warnings in Debug and Release.
• All relevant unit tests pass.
• No regression in existing functionality.

Estimated effort

2–3 days