feat(coverage): 任务新增「资产覆盖图」力导向图 tab

后端(只读，无迁移):
- db BuildCoverageGraph(taskID,expID) 复用 covTargetCTE 拉范围内全部类型资产 +
  tested 标记，补连接节点(缺失根域名/公司，灰)，按字段派生 child→parent 边
- server GET /api/tasks/{id}/coverage-graph

前端:
- 新 tab coverage-graph-tab：xyflow 渲染 + d3-force 静态力导向布局
- 已测=实色高亮、范围内未测=灰、范围外连接节点=灰虚线；点节点看详情抽屉
- 折叠/分页：同父同类型子节点默认展示 20(已测优先)，超出收进折叠节点，
  抽屉「展示更多(+20)」把下一批拉进图；布局仅在可见集合变化时重算
- types/api + d3-force 依赖声明 + 注册 tab

Co-Authored-By: Claude Opus 4.8 <[email protected]>

web/package.json

@@ -33,6 +33,7 @@
     "class-variance-authority": "^0.7.1",
     "clsx": "^2.1.1",
     "cmdk": "^1.1.1",
+    "d3-force": "^3.0.0",
     "d3-geo": "^3.1.1",
     "date-fns": "^4.4.0",
     "embla-carousel-react": "^8.6.0",
@@ -64,6 +65,7 @@
   "devDependencies": {
     "@biomejs/biome": "^2.5.1",
     "@tailwindcss/postcss": "^4.3.2",
+    "@types/d3-force": "^3.0.10",
     "@types/d3-geo": "^3.1.0",
     "@types/node": "^22.20.0",
     "@types/react": "^19.2.17",