Feature/adding matching lights path tracer and rasterizer

[juanchuletas]

Description

Introduces a first-class light data model, viewport light gizmos, and a physically based multi-light rasterizer pipeline. Replaces the hardcoded single Phong light in SceneManager with a proper light list shared across the editor, gizmo renderer, and rasterizer.

Type of Change

• New feature
• Refactor

Changes Made

• Added SceneLight struct and SceneLightType enum in Lights/light.hpp with Point, Sun, Spot, and Area types carrying position, color, power, and type-specific fields
• Added std::vector m_lights to SceneManager with addLight, getLights, and getLightCount
• Implemented LightGizmoRenderer with per-type geometry: wireframe sphere for Point, billboard quad for Sun/Spot/Area
• Introduced GizmoMesh struct for clean per-type VAO/VBO ownership
• Added gizmo_vs.glsl and gizmo_fs.glsl with billboard and world-space modes via isBillboard uniform
• Rewrote LightEditorWindow to manage the light list with add, remove, select, and edit per-light properties
• Updated fungt_default.fs and primitive_fs.glsl to support up to 8 lights via uniform array with physically based inverse square attenuation
• Updated SceneManager::renderScene() to upload the full light array and viewPos
• Fixed viewPos previously hardcoded to vec3(0, 2, 5) in the old fragment shader
• Updated FunGT::update() to call m_sceneManager->updateViewPos(m_camera.getPosition())

Technical Details

Billboard gizmo extracts camera right and up vectors directly from view matrix columns. Gizmo sphere is three great circles generated procedurally at init, uploaded as a static VAO, positioned via lightWorldPos uniform at render time. Rasterizer attenuation changed from the Ogre3D polynomial approximation to true inverse square 1/(d^2 + 1e-6) matching the path tracer scale so both renderers respond consistently to the same power value.

Testing

• Tested locally
• Visual comparison before/after

Performance Impact

No measurable impact on rasterizer path. Gizmo render adds one draw call per light.

Notes for Reviewers

Path tracer light wiring via Space::loadLightsFromScene and Area light geometry generation are intentionally out of scope and tracked separately. The core_renderer.hpp directional light branch is included as a kernel-side prerequisite for the next PR.