chore: checkpoint web Blender migration source, tools and docs

Accumulated uncommitted work: GHOST Web backend, WebGL/GPU web layer,
web workflow engine and protocol, tooling, docs and task records.
Large generated evidence, user-testing archives, build snapshots and
imported test assets remain untracked.

Co-Authored-By: Claude Code <noreply@anthropic.com>

blender-5.2.0/source/blender/gpu/shaders/common/gpu_shader_index_load_lib.glsl

@@ -29,12 +29,23 @@ uint gpu_index_load(uint element_index)
     return element_index;
   }
 
+#ifdef GPU_WEBGL
+  uint raw_index = gpu_webgl_load_gpu_index_buf(gpu_index_16bit ? element_index >> 1u :
+                                                                element_index);
+#else
   uint raw_index = gpu_index_buf[gpu_index_16bit ? element_index >> 1u : element_index];
+#endif
 
   if (gpu_index_16bit) {
     raw_index = ((element_index & 1u) == 0u) ? (raw_index & 0xFFFFu) : (raw_index >> 16u);
   }
 
+#ifdef GPU_WEBGL
+  /* Preserve fixed restart before adding the compressed buffer's base index. */
+  if (raw_index == (gpu_index_16bit ? 0xFFFFu : 0xFFFFFFFFu)) {
+    return 0xFFFFFFFFu;
+  }
+#endif
   return raw_index + uint(gpu_index_base_index);
 }
 

blender-5.2.0/source/blender/gpu/shaders/common/gpu_shader_shared_exponent_lib.glsl

@@ -69,14 +69,14 @@ uint rgb9e5_encode(float3 color)
 {
   rgb9e5_t result = rgb9e5_from_float3(color);
   result.exp_shared <<= RGB9E5_MANTISSA_BITS * 3;
-  result.mantissa <<= RGB9E5_MANTISSA_BITS * uint3(0, 1, 2);
+  result.mantissa <<= uint(RGB9E5_MANTISSA_BITS) * uint3(0, 1, 2);
   return result.mantissa.r | result.mantissa.g | result.mantissa.b | result.exp_shared;
 }
 
 float3 rgb9e5_decode(uint data)
 {
   int exp_shared = int(data >> (RGB9E5_MANTISSA_BITS * 3));
-  uint3 mantissa = (uint3(data) >> (RGB9E5_MANTISSA_BITS * uint3(0, 1, 2))) &
+  uint3 mantissa = (uint3(data) >> (uint(RGB9E5_MANTISSA_BITS) * uint3(0, 1, 2))) &
                    uint(MAX_RGB9E5_MANTISSA);
   return float3(mantissa) * rgb9e5_exponent_factor(exp_shared);
 }

blender-5.2.0/source/blender/gpu/shaders/common/gpu_shader_tiled_image_lookup_lib.glsl

@@ -6,15 +6,20 @@
 
 #include "gpu_shader_compat.hh"
 
+#ifdef GPU_WEBGL
+/* WebGL stores the single-mip tile map layers as rows. Integer fetches are unchanged. */
+bool tiled_image_lookup(float3 &co, sampler2DArray ima, sampler2D map)
+#else
 bool tiled_image_lookup(float3 &co, sampler2DArray ima, sampler1DArray map)
+#endif
 {
   float2 tile_pos = floor(co.xy);
 
-  if (tile_pos.x < 0 || tile_pos.y < 0 || tile_pos.x >= 10) {
+  if (tile_pos.x < 0.0f || tile_pos.y < 0.0f || tile_pos.x >= 10.0f) {
     return false;
   }
-  float tile = 10 * tile_pos.y + tile_pos.x;
-  if (tile >= textureSize(map, 0).x) {
+  float tile = 10.0f * tile_pos.y + tile_pos.x;
+  if (tile >= float(textureSize(map, 0).x)) {
     return false;
   }
   /* Fetch tile information. */