修复: P1-b Dashboard统计源解耦(治翻页/筛选后统计数字错乱 H6/H7)

- 统计走后端 count_tasks 独立通道,不再 filter(state.tasks) 当前页数据

- state 加 activeTaskCount/projectTaskCounts 缓存,loadStats action 并发 count 填充 + df-data-changed task 分支联动刷新

- Dashboard loadAll 删 loadTasks 改 loadStats(不再消费 state.tasks 全量)

- ActiveProjectsPanel getProjectTaskCount 改读 store.projectTaskCounts

- 后端零改(复用已注册 count_tasks IPC + count_by_query)

src/stores/project/state.ts

@@ -17,6 +17,9 @@ export const state = reactive({
   projects: [] as ProjectRecord[],
   deletedProjects: [] as ProjectRecord[],
   tasks: [] as TaskRecord[],
+  // 统计缓存,与 tasks 数组解耦,供 Dashboard,不被 Tasks 分页/筛选污染(P1-b A0)
+  activeTaskCount: 0 as number,
+  projectTaskCounts: {} as Record<string, number>,
   ideas: [] as IdeaRecord[],
   workflowExecutions: [] as WorkflowRecord[],
   liveEvents: [] as Array<WorkflowEventPayload & { _ts: number }>,