fix(canvas): 3D 导演台 - 修复白膜视频导出渲染循环逐帧崩溃 (#439)

导出白膜视频得到的是 0 秒视频：文件实测仅 1 帧（ffprobe
nb_read_frames=1，duration=0.001s），却无任何报错并照常回写画布。

根因：applyClaySceneMaterials 把场景内所有非 actor mesh 的材质换成
clay MeshStandardMaterial，drei Grid 的 GridMaterial（带 uniforms 的
ShaderMaterial）也在其中。Grid 组件内部 useFrame 每帧读取
material.uniforms.worldCamProjPosition，材质被换后 uniforms 为
undefined，渲染循环逐帧抛 TypeError，R3F 不再产出新帧，
captureStream 只录到启动前手动 gl.render 的那一帧；5 秒后
setTimeout 照常 stop，残缺视频被当作成功结果。开启轨迹显示
（drei Line 同为 uniforms 材质）或视口白膜显示模式时同样触发。

修复：
- applyClaySceneMaterials 跳过带 uniforms 的 ShaderMaterial，
  并抽到 lib/canvas/director/director-clay-materials.ts 补回归测试；
- recordCanvas 加固：录制期间监听 window 未捕获错误，首个渲染
  错误立即中止并报错；录制结束用 <video> 探测真实时长（Chrome
  MediaRecorder 的 webm 无时长头，需 seek 到末尾），低于预期一半
  报「时长异常」，杜绝残缺视频再被静默回写。

web/package.json

@@ -10,7 +10,7 @@
         "pretest": "bun test test/tiptap-dependency-versions.test.ts test/admin-ui-regressions.test.ts test/announcement-prompt-regressions.test.ts test/password-reset.test.ts test/oss-settings.test.ts test/channel-model-editor-form.test.ts test/channel-model-price-tier-form.test.ts test/admin-logical-models.test.ts && bun test test/canvas-grid-viewport.test.tsx",
         "typecheck": "tsc --noEmit",
         "test:canvas": "bun test test/canvas-media-performance.test.ts test/canvas-node-title-interaction.test.ts test/canvas-spatial-index.test.ts",
-        "test": "bun test test/api-request.test.ts test/video-api-contracts.test.ts test/image-api-contracts.test.ts test/channel-model-catalog.test.ts test/model-pricing.test.ts test/model-protocols.test.ts test/model-capabilities.test.ts test/agent-prompt-cache.test.ts test/canvas-agent-context.test.ts test/canvas-batch-connection.test.ts test/canvas-character-reference.test.ts test/canvas-document.test.ts test/canvas-drawing-engine.test.ts test/canvas-emotion-edit-plan.test.ts test/canvas-extension-nodes.test.ts test/canvas-folder.test.ts test/canvas-generation-layout.test.ts test/canvas-generation-submission.test.ts test/canvas-image-batch-retry.test.ts test/canvas-keyboard.test.ts test/canvas-node-generation-mentions.test.ts test/canvas-node-search.test.ts test/canvas-leafer-viewport.test.ts test/canvas-media-download.test.ts test/canvas-local-runtime.test.ts test/canvas-model-policy.test.ts test/canvas-resource-mention-editor.test.ts test/canvas-resource-references.test.ts test/canvas-storyboard-assets.test.ts test/canvas-storyboard-references.test.ts test/canvas-node-config-reset.test.ts test/canvas-node-registry.test.ts test/canvas-video-frame.test.ts test/canvas-video-regeneration.test.ts test/canvas-video-timeline-segments.test.ts test/create-canvas-handoff.test.ts test/create-library-button.test.ts test/creation-references.test.ts test/director-transform-semantics.test.ts test/director-bone-precedence.test.ts test/director-gesture-transaction.test.ts test/director-transaction-lifecycle.test.ts test/director-session-authority.test.ts test/director-placement.test.ts test/director-resources.test.ts test/director-recovery.test.ts test/director-node-preview.test.ts test/generation-asset-repository.node.test.ts test/generation-storage-consistency.test.ts test/generation-task-durability.node.test.ts test/generation-task-local.test.ts test/generation-task-materializer.test.ts test/task-media-fallback.test.ts test/user-scoped-generation-persistence.test.ts test/local-channel-permission.test.ts test/local-channel-runtime-projection.node.test.mjs test/local-channel-task-center.node.test.mjs test/local-channel-ui.node.test.mjs test/local-cli-settings.test.ts test/local-dreamina-cli.test.ts test/local-dreamina-generation.test.ts test/local-dreamina-model-catalog.test.ts test/local-runtime-bootstrap.test.ts test/local-runtime-connection.test.ts test/local-runtime.test.ts test/client-id.test.ts test/grok-image-prompt-limit.test.ts test/image-resolution-tiers.test.ts test/gemini-image.test.ts test/libtv-import.test.ts test/timeline-to-ffmpeg.test.ts test/canvas-video-segment-args.test.ts test/tapnow-import.test.ts test/prompt-optimizer-drawer.test.ts test/director-save-coordinator.test.ts test/director-save-wiring.test.ts test/director-diagnostics.test.ts test/director-repro-runtime.test.ts test/director-diagnostics-recorder.test.ts test/director-keyframe-editing.test.ts test/director-shortcuts.test.ts test/director-keyframe-delete-wiring.test.ts test/director-templates.test.ts test/director-modes.test.ts test/director-template-mode-wiring.test.ts test/director-view-modes.test.ts && bun test test/local-dreamina-cross-runtime.test.ts",
+        "test": "bun test test/api-request.test.ts test/video-api-contracts.test.ts test/image-api-contracts.test.ts test/channel-model-catalog.test.ts test/model-pricing.test.ts test/model-protocols.test.ts test/model-capabilities.test.ts test/agent-prompt-cache.test.ts test/canvas-agent-context.test.ts test/canvas-batch-connection.test.ts test/canvas-character-reference.test.ts test/canvas-document.test.ts test/canvas-drawing-engine.test.ts test/canvas-emotion-edit-plan.test.ts test/canvas-extension-nodes.test.ts test/canvas-folder.test.ts test/canvas-generation-layout.test.ts test/canvas-generation-submission.test.ts test/canvas-image-batch-retry.test.ts test/canvas-keyboard.test.ts test/canvas-node-generation-mentions.test.ts test/canvas-node-search.test.ts test/canvas-leafer-viewport.test.ts test/canvas-media-download.test.ts test/canvas-local-runtime.test.ts test/canvas-model-policy.test.ts test/canvas-resource-mention-editor.test.ts test/canvas-resource-references.test.ts test/canvas-storyboard-assets.test.ts test/canvas-storyboard-references.test.ts test/canvas-node-config-reset.test.ts test/canvas-node-registry.test.ts test/canvas-video-frame.test.ts test/canvas-video-regeneration.test.ts test/canvas-video-timeline-segments.test.ts test/create-canvas-handoff.test.ts test/create-library-button.test.ts test/creation-references.test.ts test/director-transform-semantics.test.ts test/director-bone-precedence.test.ts test/director-clay-materials.test.ts test/director-gesture-transaction.test.ts test/director-transaction-lifecycle.test.ts test/director-session-authority.test.ts test/director-placement.test.ts test/director-resources.test.ts test/director-recovery.test.ts test/director-node-preview.test.ts test/generation-asset-repository.node.test.ts test/generation-storage-consistency.test.ts test/generation-task-durability.node.test.ts test/generation-task-local.test.ts test/generation-task-materializer.test.ts test/task-media-fallback.test.ts test/user-scoped-generation-persistence.test.ts test/local-channel-permission.test.ts test/local-channel-runtime-projection.node.test.mjs test/local-channel-task-center.node.test.mjs test/local-channel-ui.node.test.mjs test/local-cli-settings.test.ts test/local-dreamina-cli.test.ts test/local-dreamina-generation.test.ts test/local-dreamina-model-catalog.test.ts test/local-runtime-bootstrap.test.ts test/local-runtime-connection.test.ts test/local-runtime.test.ts test/client-id.test.ts test/grok-image-prompt-limit.test.ts test/image-resolution-tiers.test.ts test/gemini-image.test.ts test/libtv-import.test.ts test/timeline-to-ffmpeg.test.ts test/canvas-video-segment-args.test.ts test/tapnow-import.test.ts test/prompt-optimizer-drawer.test.ts test/director-save-coordinator.test.ts test/director-save-wiring.test.ts test/director-diagnostics.test.ts test/director-repro-runtime.test.ts test/director-diagnostics-recorder.test.ts test/director-keyframe-editing.test.ts test/director-shortcuts.test.ts test/director-keyframe-delete-wiring.test.ts test/director-templates.test.ts test/director-modes.test.ts test/director-template-mode-wiring.test.ts test/director-view-modes.test.ts && bun test test/local-dreamina-cross-runtime.test.ts",
         "test:director:e2e": "bun scripts/director-p0-chrome-e2e.mjs",
         "start": "vite preview --host 0.0.0.0 --port 3000",
         "format": "prettier --write .",