feat(renderer): add RT reflections, RT AO, and RT point/spot shadows

Add three new compute shader modules extending the existing RT shadow system:
- RT Reflections: screen-space reflection ray marching from G-Buffer
- RT Ambient Occlusion: hemisphere sampling with cosine-weighted directions
- RT Point/Spot Shadow: placeholder infrastructure for point/spot light shadows

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/voltex_renderer/src/lib.rs

@@ -30,6 +30,9 @@ pub mod deferred_pipeline;
 pub mod ssgi;
 pub mod rt_accel;
 pub mod rt_shadow;
+pub mod rt_reflections;
+pub mod rt_ao;
+pub mod rt_point_shadow;
 pub mod hdr;
 pub mod bloom;
 pub mod tonemap;
@@ -76,6 +79,9 @@ pub use deferred_pipeline::{
 pub use ssgi::{SsgiResources, SsgiUniform, SSGI_OUTPUT_FORMAT};
 pub use rt_accel::{RtAccel, RtInstance, BlasMeshData, mat4_to_tlas_transform};
 pub use rt_shadow::{RtShadowResources, RtShadowUniform, RT_SHADOW_FORMAT};
+pub use rt_reflections::RtReflections;
+pub use rt_ao::RtAo;
+pub use rt_point_shadow::RtPointShadow;
 pub use hdr::{HdrTarget, HDR_FORMAT};
 pub use bloom::{BloomResources, BloomUniform, mip_sizes, BLOOM_MIP_COUNT};
 pub use tonemap::{TonemapUniform, aces_tonemap};