Implement FSR 2.2 temporal upscaling

Full FSR 2.2 pipeline with depth-based motion vector reprojection,
temporal accumulation with YCoCg neighborhood clamping, and RCAS
contrast-adaptive sharpening.

Architecture (designed for FSR 3.x frame generation readiness):
- Camera: Halton(2,3) sub-pixel jitter with unjittered projection
  stored separately for motion vector computation
- Motion vectors: compute shader reconstructs world position from
  depth + inverse VP, reprojects with previous frame's VP
- Temporal accumulation: compute shader blends 5-10% current frame
  with 90-95% clamped history, adaptive blend for disocclusion
- History: ping-pong R16G16B16A16 buffers at display resolution
- Sharpening: RCAS fragment pass with contrast-adaptive weights

Integration:
- FSR2 replaces both FSR1 and MSAA when enabled
- Scene renders to internal resolution framebuffer (no MSAA)
- Compute passes run between scene and swapchain render passes
- Camera cut detection resets history on teleport
- Quality presets shared with FSR1 (0.50-0.77 scale factors)
- UI: "Upscaling" combo with Off/FSR 1.0/FSR 2.2 options

include/rendering/camera.hpp

@@ -23,9 +23,16 @@ public:
     const glm::vec3& getPosition() const { return position; }
     const glm::mat4& getViewMatrix() const { return viewMatrix; }
     const glm::mat4& getProjectionMatrix() const { return projectionMatrix; }
+    const glm::mat4& getUnjitteredProjectionMatrix() const { return unjitteredProjectionMatrix; }
     glm::mat4 getViewProjectionMatrix() const { return projectionMatrix * viewMatrix; }
+    glm::mat4 getUnjitteredViewProjectionMatrix() const { return unjitteredProjectionMatrix * viewMatrix; }
     float getAspectRatio() const { return aspectRatio; }
 
+    // Sub-pixel jitter for temporal upscaling (FSR 2)
+    void setJitter(float jx, float jy);
+    void clearJitter();
+    glm::vec2 getJitter() const { return jitterOffset; }
+
     glm::vec3 getForward() const;
     glm::vec3 getRight() const;
     glm::vec3 getUp() const;
@@ -46,6 +53,8 @@ private:
 
     glm::mat4 viewMatrix = glm::mat4(1.0f);
     glm::mat4 projectionMatrix = glm::mat4(1.0f);
+    glm::mat4 unjitteredProjectionMatrix = glm::mat4(1.0f);
+    glm::vec2 jitterOffset = glm::vec2(0.0f);  // NDC jitter (applied to projection)
 };
 
 } // namespace rendering