feat(engine): add DiamondSquare and improve rendering architecture

feat(engine): add DiamondSquare and improve rendering architecture

Add DiamondSquare algorithm for procedural terrain heightmap generation.
Merge Rotation class into Quaternion for unified rotation handling.
Introduce global LightingManager in ViewPanel for scene-wide lighting.
Fix text rendering to use per-segment Graphics2D for proper clipping.
Fix raytracer camera frame to use inverse rotation.
Add comprehensive documentation for perspective-correct texture mapping.
Simplify debug log buffer by removing passthrough feature.

Squashed commits:
- fix(raytracer): use inverse rotation when placing camera frame
- refactor(gui): remove stdout passthrough from debug log buffer
- fix(render): use per-segment Graphics2D to clip text rendering
- docs: add CUSTOM_ID properties to all org-mode sections
- feat(math): add DiamondSquare algorithm and document composite shape fields
- refactor(gui): improve developer tools and composite shape logging
- refactor(lighting): use global LightingManager in ViewPanel
- refactor(math): merge Rotation into Quaternion
- docs: move perspective texture docs to dedicated directory