Shadow map is bound to texture slot 3: the roughness slot: on both DX11 and OpenGL #145

src/Graphics/DirectX11/DirectX11Renderer.cpp:189-190, :1203-1204;
src/Graphics/OpenGL/OpenGLRenderer.cpp:779-781, :1091-1093;
include/public/Runtime/Material.hpp:18; src/Graphics/Common/Material.cpp:37, :113

Both backends bind the shadow map to slot 3:

• DX11: PSSetShaderResources(3, ...)
• GL: GL_TEXTURE3

But every shader declares the shadow map at 11/12, not 3:

• default_shader.hlsl:101: Texture2D roughnessTexture : register(t3); shadow map is t11/s1/s2 at :216-218
• default_shader_gl.frag:89: roughnessTexture at binding 3; shadow bindings 11/12 at :170-171

And TEXTURE_SLOT_ROUGHNESS is 3 (Material.hpp:18), bound per draw at Material.cpp:37/:113.

Two consequences, both live:

1. Nothing ever binds t11/t12 on either backend, yet ShadowMapEnabled is set to 1
   (DirectX11Renderer.cpp:1225, OpenGLRenderer.cpp:679): so CalcShadow runs against an unbound
   resource. Shadows are broken on DX11 and GL forward.
2. Slot 3 is fought over per draw. A material with no roughness map samples the shadow depth texture as
   PBR roughness: wrong shading, varying with the light's view.

Corroborating evidence this is a known-but-unfixed issue: the GL renderer already carries a workaround
comment plus an unbind for exactly this collision at OpenGLRenderer.cpp:1005-1009: but it only covers the
GBuffer pass, not the forward pass.

Severity: corruption (wrong texture sampled as a material parameter) + visual (no shadows).

Found by a full audit of the graphics layer. Assessed severity: corruption + visual.