refactor(canvas): 节点注册表 - 收敛素材类型、生成模式与输入计数判据

把三条按类型分支的语义判据收进注册表：
- resourceKind  原 canvas-resource-references.ts，作为 @ 引用素材时的类型
- generationMode 原 canvas-connection-policy.ts，作为生成节点时的模式
- inputKind     原 canvas-connection-policy.ts，被容量校验计数时的类别

resourceKind 与 inputKind 刻意分成两个字段：它们语义不同——空图片节点不是素材
（不进 @ 引用），但照样计入 imageCount。合成一个会静默改掉连线容量校验。

两处必须保住的语义，均已由测试钉住：
1. 角色卡（workflowKind === character）是跨类型覆盖，对任何节点类型生效，
   属于查注册表之前的前置判定，因此留在调用点而不进 per-type 定义。
2. 排除必须早于覆盖。原实现先 return 掉生成配置与背板，之后才判角色卡；
   若把角色卡判定提前，带角色元数据的配置/背板节点会被多算成 characterCount。

新增 test/canvas-node-registry.test.ts（19 用例 / 77 断言）并加入 package.json
的 test 列表——该列表是显式枚举，不加进去文件不会跑。补测的原因是
canvas-resource-references.test.ts 只覆盖 collectUpstreamVideoNodes，
本次改动的 resourceKind 此前零覆盖，而这类判据出错不报错、只会让 @ 引用少收素材。

顺带内联 nodeGenerationMode（迁移后退化为单行转发）。

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

web/src/lib/canvas/canvas-connection-policy.ts

@@ -1,6 +1,7 @@
 import { maxModelInputCapacity, type ModelInputSummary } from "@/lib/model-selection";
+import { getNodeGenerationMode, getNodeInputKind } from "@/lib/canvas/node-registry";
 import type { AiConfig } from "@/stores/use-config-store";
-import { CanvasNodeType, type CanvasConnection, type CanvasGenerationMode, type CanvasNodeData } from "@/types/canvas";
+import { type CanvasConnection, type CanvasNodeData } from "@/types/canvas";
 
 type ConnectionCandidate = Pick<CanvasConnection, "fromNodeId" | "toNodeId">;
 type CanvasConnectionPolicyOptions = {
@@ -11,7 +12,7 @@ type CanvasConnectionPolicyOptions = {
 export function canvasConnectionError(config: AiConfig, nodes: CanvasNodeData[], connections: CanvasConnection[], candidate: ConnectionCandidate, options: CanvasConnectionPolicyOptions = {}) {
     const target = nodes.find((node) => node.id === candidate.toNodeId);
     if (!target) return "找不到连线目标节点";
-    const mode = nodeGenerationMode(target);
+    const mode = getNodeGenerationMode(target);
     if (!mode) return "";
     const input = connectionInputSummary(target.id, nodes, connections, candidate);
     const visualInputCount = input.imageCount + input.characterCount;
@@ -35,25 +36,18 @@ export function connectionInputSummary(targetNodeId: string, nodes: CanvasNodeDa
     const input: ModelInputSummary = { textCount: 0, imageCount: 0, videoCount: 0, audioCount: 0, characterCount: 0 };
     sourceIds.forEach((sourceId) => {
         const source = nodes.find((node) => node.id === sourceId);
-        if (!source || source.type === CanvasNodeType.Config || source.type === CanvasNodeType.Frame) return;
+        if (!source) return;
+        // 生成配置与背板不是参考素材，不参与容量计数——这一步必须早于角色卡判定，
+        // 否则一个带角色元数据的配置/背板节点会被多算成角色。
+        const inputKind = getNodeInputKind(source.type);
+        if (!inputKind) return;
+        // 角色卡是跨类型覆盖：落在可计数类型上时改记为角色。
         if (source.metadata?.workflowKind === "character") input.characterCount += 1;
-        else if (source.type === CanvasNodeType.Image || source.type === CanvasNodeType.Drawing) input.imageCount += 1;
-        else if (source.type === CanvasNodeType.Video) input.videoCount += 1;
-        else if (source.type === CanvasNodeType.Audio) input.audioCount += 1;
-        else input.textCount += 1;
+        else input[`${inputKind}Count`] += 1;
     });
     return input;
 }
 
-function nodeGenerationMode(node: CanvasNodeData): CanvasGenerationMode | null {
-    if (node.type === CanvasNodeType.Config) return node.metadata?.generationMode || "image";
-    if (node.type === CanvasNodeType.Image) return "image";
-    if (node.type === CanvasNodeType.Video) return "video";
-    if (node.type === CanvasNodeType.Audio) return "audio";
-    if (node.type === CanvasNodeType.Text || node.type === CanvasNodeType.Script) return "text";
-    return null;
-}
-
 function capacityError(config: AiConfig, capability: "image" | "video", kind: "image" | "video" | "audio", count: number, label: string) {
     const maximum = maxModelInputCapacity(config, capability, kind);
     if (maximum === null || count <= maximum) return "";