[Feature] Support large-world and scene-aware navigation modes

[JeanPhilippeKernel]

Type

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

Overview

The initial editor camera is free-fly/orbit oriented. Large production scenes require predictable depth precision, scene-aware navigation, and optional walk/ground-constrained movement.

Context

This is a follow-up after real scene raycasts and robust input ownership. It should not add large-world precision complexity to the current viewport correctness fixes.

Depends on #781 and #782.

What needs to be done

1. Define near/far-plane and depth-precision policy for editor cameras.
2. Evaluate and implement editor origin rebasing or high-precision camera/world coordinates where scene scale requires it.
3. Add optional terrain/geometry collision, ground lock, and walk mode.
4. Define Free, Orbit, and Walk navigation modes with visible state/UI feedback.
5. Use selection bounds or cursor-hit results for scene-aware pivots.
6. Document behavior, limits, and migration implications for existing scenes.

Resources

• ZEngine/ZEngine/Rendering/Cameras/FlyCamera.cpp
• Tetragrama/Controllers/EditorCameraController.cpp
• ZEngine/ZEngine/Rendering/Scenes/RenderScene.h
• ZEngine/docs/future-plan/fly-camera-redesign.md

Testing

• Add numeric stability tests for configured large-world ranges.
• Add CPU tests for navigation-mode transitions and collision/ground-lock behavior.
• Manually test free, orbit, and walk workflows on representative large scenes.

Acceptance criteria

• Camera depth policy is documented and validated for target scene scales.
• Large-world precision strategy is selected and implemented where needed.
• Free, Orbit, and optional Walk modes have explicit, testable behavior.
• Scene-aware pivots and optional collision are available through the ray-query layer.
• Existing free-fly workflow remains available.
• Builds without warnings in Debug and Release.
• All relevant unit tests pass.
• No regression in existing functionality.

Estimated effort

2–4 weeks