Implement TSAA (Temporal Specular Anti-Aliasing) pipeline

[Copilot]

Adds a full temporal anti-aliasing pass to the forward rendering pipeline: Forward → TSAA → PostProcessing → Present.

New files

• TSAAPass.h/cpp — FullScreenPass subclass managing two persistent RGBA16F images in ping-pong for history reprojection. Handles resolution changes by recreating buffers.
• tsaa.hlsl — Per-pixel motion vectors via inv(ViewProj) cofactor inverse, 3×3 dilated closest-depth lookup, Karis '14 variance-based neighborhood clamping in Reinhard-tonemapped space, velocity-adaptive blend (5–12%).
• tsaa.tech — Fullscreen technique definition (no depth, no cull).

Pipeline integration (DefaultForwardPipeline)

• Generates Halton(2,3) sub-pixel jitter (16-sample cycle), applies to projection matrix via new SceneView::SetJitter(), and writes jitter UV to ShaderPassInfo.
• Inserts TSAAPass between forward and post-processing. PostProcessingPass now reads TSAAColor instead of ForwardColor.

Core changes

• SceneView — SetJitter(float, float) offsets projects[i] columns 2,0/2,1 before computing viewProject. Jitter bakes into both current and lastViewProject, so motion vectors are correct without explicit unjitter.
• ShaderPassInfo — Appended Vector4 jitter (trailing field, no ABI break for existing shaders that only read up to Viewport).
• PostProcessingPass — Constructor now takes optional std::string_view inputColorName defaulting to FWD_CL for backward compatibility.
• DefaultPassConstants — Added TSAA_CL, TSAA_HIST.

Shader algorithm sketch

// 1. Dilated depth → closest 3×3 neighbor for edge-stable motion vectors
// 2. inv(ViewProj) * clipPos → worldPos → LastViewProj → prevUV
// 3. Variance clip: μ ± 1.25σ clamped to min/max AABB in tonemapped space
// 4. blend = lerp(0.05, 0.12, saturate(|velocity| * 20))
// 5. Reject history if reprojected UV is offscreen
result = lerp(clampedHistory, currentColor, blend);

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