feat(web): 攻击链路图渲染压缩(digest)节点并收缩其成员

- ExploreKind/ExploreRel 增加 digest/covers 类型
- digest 节点独立样式(青色 Layers)、图例与摘要(body)
- collapseDigestGraph：active digest 覆盖的 fact/intent 成员从图中隐藏，
  触及成员的边端点改接到 digest，成员内部边丢弃并去重，covers 边不渲染
- 详情抽屉展示压缩结论与被压缩成员列表，成员可点击下钻

web/src/lib/types.ts

@@ -401,12 +401,12 @@ export interface Company {
 }
 
 // ---- Exploration graph (per task) ----
-export type ExploreKind = "task" | "begin" | "goal" | "intent" | "fact" | "finding" | "hint";
+export type ExploreKind = "task" | "begin" | "goal" | "intent" | "fact" | "finding" | "hint" | "digest";
 export type GoalState = "open" | "met" | "abandoned";
 export type IntentState = "open" | "running" | "paused" | "done" | "blocked" | "exhausted" | "stopped";
 export type FindingState = "confirmed" | "dismissed";
 export type HintState = "active" | "consumed";
-export type ExploreRel = "spawns" | "derived_from" | "yields" | "proves";
+export type ExploreRel = "spawns" | "derived_from" | "yields" | "proves" | "covers";
 
 export interface TaskNode {
   id: string;