Added textures

SHADER_CONTRACT.md

@@ -15,6 +15,7 @@ Each shader package lives under `shaders/<id>/` and includes:
 - `category`
 - `entryPoint`
 - `parameters`
+- optional `textures`
 - optional `temporal`
 
 Supported parameter types:
@@ -25,6 +26,25 @@ Supported parameter types:
 - `bool`
 - `enum`
 
+## Texture assets
+
+Shaders can optionally declare texture assets:
+
+```json
+{
+  "textures": [
+    {
+      "id": "logoTexture",
+      "path": "logo.png"
+    }
+  ]
+}
+```
+
+- `id` becomes a shader-visible sampler name
+- `path` is resolved relative to the shader package directory
+- texture asset changes trigger shader reload just like shader and manifest edits
+
 ## Temporal manifests
 
 Shaders can optionally declare temporal history needs:
@@ -86,3 +106,9 @@ Helper function:
 - `sampleVideo(float2 uv)` returns decoded full-resolution RGBA video from the live DeckLink input.
 - `sampleSourceHistory(int framesAgo, float2 uv)` samples the most recent available source history frame, clamping to the oldest available frame if needed.
 - `sampleTemporalHistory(int framesAgo, float2 uv)` samples the most recent available pre-layer history frame for temporal shaders, clamping to the oldest available frame if needed.
+
+Declared texture assets are exposed as `Sampler2D<float4>` globals using the texture `id`, for example:
+
+```slang
+float4 logo = logoTexture.Sample(uv);
+```