feat(canvas): 扩展节点 - 新增 7 种展示与加工节点并补齐上游读取基建

在已落地的节点注册表上加两层节点：展示层（Markdown / SVG / HTML / 全景）与
接入生成链的加工层（对比 / 图表 / 调色）。全部是第一方内置节点，不引入远程插件
加载，因此不涉及沙箱信任模型，也不需要把 CanvasNodeType 放开成任意字符串。

刻意保留穷尽性检查而不是改成运行时注册。全库只有 4 张按类型建的穷眉表
（NODE_DEFAULT_SIZE / NODE_SPECS / 注册表定义 / nodeContentRenderers），
让编译器强制每个新节点填满它们，比少改几个文件更值 —— 加第一个枚举成员时
编译器点出了 5 处，其中 pages/canvas/shared.tsx 是原先没编目的那一处；
换成运行时注册，那里会静默回落成「未知节点」。

两处前置基建：
- CanvasNodeGraphContext：渲染器只拿到 node、没有 connections，而加工层三个节点
  都要读上游。仿已有的 canvas-node-action-context（同一个问题：节点经
  CanvasProjectWorldLayers 渲染不便逐个透传），取上游复用
  canvas-resource-references 的 getContextResourceNodes，不另写一份。
  Provider 值必须 memo —— 每帧新对象会让所有节点跟着重渲染。
- ToolbarHandlers.onAddExtensionNode(type)：一个泛用入口，不给每种扩展节点单开
  一个 onAddXxx。菜单另开「展示与加工」分区，不挤占上方调好的四列创作网格。

SVG 与 HTML 统一走 sandbox iframe：依赖里没有 DOMPurify，手写 SVG 消毒不可靠
（script / on* / foreignObject）。SandboxedFrame 只暴露 allowScripts 布尔而不是
sandbox 取值，让「同时给 allow-same-origin」这条没有入口。

全景节点三个取舍：点击才激活 WebGL（浏览器对同时存在的上下文有硬上限，画布可以有
任意多个全景节点，自动激活必然在某个数量后整片黑）；用原生 three 而非 fiber
（需要精确 dispose，forceContextLoss 才真正释放上下文）；性能模式下只给静态预览。

调色是唯一碰生成路径的节点，照 Drawing 的先例：拖滑杆只做本地 CSS filter 预览，
落地成资源要等到生成消费它时才走 uploadResourceFile。预览与导出共用同一个
filter 字符串，两处各写一份就会「看到的和用的悄悄不一致」；未调色时直接透传源图，
省掉一次渲染与上传。ctx.filter 不受支持时明确报错而不是导出一张没调色的图。

resourceKind 与 inputKind 分开两个字段：空图片节点不是素材（不进 @ 引用），
但照样计入 imageCount。调色节点的 resourceKind 无条件返回 image —— 它的图来自
上游，按「有没有 content」判断会让它永远进不了生成输入，这是不报错的静默失效。

测试：新增 test/canvas-extension-nodes.test.ts（12 用例 / 64 断言），覆盖 7 个节点的
判据矩阵、调色参数、以及图表解析。图表解析函数刻意不抛 —— 数据来自模型输出，
非法 JSON 是常态而不是异常，抛出来会连带整个画布白屏，有 7 条断言钉这个。
测试列表是显式枚举，已把新文件加进 package.json，不加进去不会跑。

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

web/package.json

@@ -7,7 +7,7 @@
         "dev": "vite --host 0.0.0.0 --port 3000",
         "build": "tsc --noEmit && vite build",
         "typecheck": "tsc --noEmit",
-        "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/agent-prompt-cache.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-folder.test.ts test/canvas-generation-layout.test.ts test/canvas-image-batch-retry.test.ts test/canvas-leafer-viewport.test.ts test/canvas-local-runtime.test.ts test/canvas-model-policy.test.ts test/canvas-resource-references.test.ts test/canvas-storyboard-references.test.ts test/canvas-node-config-reset.test.ts test/canvas-node-registry.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/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 && 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/agent-prompt-cache.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-image-batch-retry.test.ts test/canvas-leafer-viewport.test.ts test/canvas-local-runtime.test.ts test/canvas-model-policy.test.ts test/canvas-resource-references.test.ts test/canvas-storyboard-references.test.ts test/canvas-node-config-reset.test.ts test/canvas-node-registry.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/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 && bun test test/local-dreamina-cross-runtime.test.ts",
         "start": "vite preview --host 0.0.0.0 --port 3000",
         "format": "prettier --write .",
         "format:check": "prettier --check ."