feat(web): complete PBR shader, asset library and offscreen render chain

- generate a desktop-Blender PBR asset library and seed catalog v2 into OPFS
- add React asset browser, material preview sphere and Web PBR render panel
- extend shader graph/compiler to the finite 14-node set and native properties
- add image colour-space editing, scene-camera still rendering and asset repair
- add focused E2E/unit coverage and implementation status notes

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

web/tests/unit/local-deps.test.mjs

@@ -11,7 +11,7 @@ const packageJson = JSON.parse(
 
 test("browser runtime dependencies stay local", () => {
   const runtimePackages = Object.keys(packageJson.dependencies ?? {});
-  assert.deepEqual([...runtimePackages].sort(), ["@ffmpeg/core", "@ffmpeg/ffmpeg", "@ffmpeg/util", "@webgpu/glslang", "fflate", "naga-wasm", "react", "react-dom"].sort());
+  assert.deepEqual([...runtimePackages].sort(), ["@ffmpeg/core", "@ffmpeg/ffmpeg", "@ffmpeg/util", "@webgpu/glslang", "@xyflow/react", "fflate", "naga-wasm", "react", "react-accessible-treeview", "react-dom"].sort());
   assert.equal(packageJson.dependencies?.three, undefined);
   assert.equal(packageJson.dependencies?.["@sqlite.org/sqlite-wasm"], undefined);
   for (const name of runtimePackages) {