feat: 开发任务时间字段重构 + 双口径耗时 + 搜索 + 性能优化

核心变更:
- DevTask 字段重构：startDate/dueDate/estimateHours/actualHours 替换为 expectedStartAt/expectedEndAt/actualStartAt/actualEndAt（含时分），预计/实际工时按工作时段（9:00-12:00 + 13:00-18:00）派生计算
- 状态机自动化：到点自动切开发中、未到可手动开干、超期需填延后原因
- 新建 lib/work-hours.ts：calcWorkHours（工作时段过滤）、formatWorkHours（X h（Y 天））、calcTwoMetrics（日历/人力双口径）
- 新建 lib/dev-task-transitions.ts：状态切换守卫
- 三个 Tab 顶部统计：开发任务（预/日历/人力）、测试用例 / Bug（日历 / 人力）；版本概览总人天投入改双行（日历总耗时 / 人力总投入）
- 三个 Tab 加搜索框：300ms debounce + 标题/编号模糊匹配
- 性能优化：requirementIds/categories/requirements/testCases 转 Map/Set 索引、Row 组件 React.memo
- 全局耗时显示统一带天数换算：8h（1天）、11h（1.4天）

新增文件: SearchInput.tsx, useDebouncedValue.ts, work-hours.ts, dev-task-transitions.ts, 设计文档

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/stores/useDevTaskStore.ts

@@ -1,9 +1,11 @@
 'use client';
 import { create } from 'zustand';
 import type { DevTask, DevTaskStatus } from '@/lib/dev-task';
-import { canTransition, generateTaskNo } from '@/lib/dev-task';
+import { canTransition, generateTaskNo, isLegacyTask } from '@/lib/dev-task';
+import { findTasksToAutoStart, deriveActualStartAt } from '@/lib/dev-task-transitions';
 
-const STORAGE_KEY = 'ftb_dev_tasks_v1';
+const STORAGE_KEY = 'ftb_dev_tasks_v2';
+const LEGACY_KEY = 'ftb_dev_tasks_v1';
 
 function saveLocal(items: DevTask[]) {
   try { localStorage.setItem(STORAGE_KEY, JSON.stringify(items)); } catch {}
@@ -12,7 +14,17 @@ function saveLocal(items: DevTask[]) {
 function loadLocal(): DevTask[] | null {
   try {
     const raw = localStorage.getItem(STORAGE_KEY);
-    if (raw) return JSON.parse(raw);
+    if (raw) {
+      const parsed = JSON.parse(raw);
+      if (Array.isArray(parsed) && parsed.some(isLegacyTask)) {
+        localStorage.removeItem(STORAGE_KEY);
+        return null;
+      }
+      return parsed;
+    }
+    if (localStorage.getItem(LEGACY_KEY)) {
+      localStorage.removeItem(LEGACY_KEY);
+    }
   } catch {}
   return null;
 }
@@ -20,12 +32,11 @@ function loadLocal(): DevTask[] | null {
 interface DevTaskState {
   tasks: DevTask[];
   fetchTasks: () => void;
-  createTask: (data: Omit<DevTask, 'id' | 'taskNo' | 'createdAt' | 'updatedAt' | 'actualHours' | 'isBlocked'>) => DevTask;
+  createTask: (data: Omit<DevTask, 'id' | 'taskNo' | 'createdAt' | 'updatedAt' | 'isBlocked'>) => DevTask;
   updateTask: (id: string, data: Partial<DevTask>) => void;
   deleteTask: (id: string) => void;
-  changeStatus: (id: string, to: DevTaskStatus) => { ok: boolean; message?: string };
+  changeStatus: (id: string, to: DevTaskStatus, opts?: { delayReason?: string }) => { ok: boolean; message?: string };
   setBlocked: (id: string, blocked: boolean, reason?: string, blockedById?: string) => void;
-  syncActualHours: (taskId: string, hours: number) => void;
   getByRequirement: (requirementId: string) => DevTask[];
   getByVersionViaRequirements: (requirementIds: string[]) => DevTask[];
   getByAssignee: (assigneeId: string) => DevTask[];
@@ -36,7 +47,21 @@ export const useDevTaskStore = create<DevTaskState>((set, get) => ({
 
   fetchTasks: () => {
     const cached = loadLocal();
-    if (cached) set({ tasks: cached });
+    const list = cached ?? [];
+    const now = new Date();
+    const autoStarts = findTasksToAutoStart(list, now);
+    if (autoStarts.length > 0) {
+      const map = new Map(autoStarts.map((a) => [a.taskId, a.actualStartAt]));
+      const updated = list.map((t) =>
+        map.has(t.id)
+          ? { ...t, status: 'in_progress' as DevTaskStatus, actualStartAt: map.get(t.id)!, updatedAt: now.toISOString() }
+          : t,
+      );
+      set({ tasks: updated });
+      saveLocal(updated);
+    } else {
+      set({ tasks: list });
+    }
   },
 
   createTask: (data) => {
@@ -46,7 +71,6 @@ export const useDevTaskStore = create<DevTaskState>((set, get) => ({
       ...data,
       id: `task-${Date.now()}`,
       taskNo: generateTaskNo(list),
-      actualHours: 0,
       isBlocked: false,
       createdAt: now,
       updatedAt: now,
@@ -71,16 +95,22 @@ export const useDevTaskStore = create<DevTaskState>((set, get) => ({
     saveLocal(updated);
   },
 
-  changeStatus: (id, to) => {
+  changeStatus: (id, to, opts) => {
     const task = get().tasks.find((t) => t.id === id);
     if (!task) return { ok: false, message: '任务不存在' };
     if (!canTransition(task.status, to)) {
       return { ok: false, message: `不允许从「${task.status}」流转到「${to}」` };
     }
-    const now = new Date().toISOString();
-    const startDate = (to === 'in_progress' && !task.startDate) ? now : task.startDate;
-    const completedAt = (to === 'submitted' && !task.completedAt) ? now : task.completedAt;
-    get().updateTask(id, { status: to, startDate, completedAt });
+    const now = new Date();
+    const patch: Partial<DevTask> = { status: to };
+    if (to === 'in_progress' && !task.actualStartAt) {
+      patch.actualStartAt = deriveActualStartAt(task, 'manual', now);
+      if (opts?.delayReason) patch.delayReason = opts.delayReason;
+    }
+    if (to === 'submitted') {
+      patch.actualEndAt = now.toISOString();
+    }
+    get().updateTask(id, patch);
     return { ok: true };
   },
 
@@ -92,10 +122,6 @@ export const useDevTaskStore = create<DevTaskState>((set, get) => ({
     });
   },
 
-  syncActualHours: (taskId, hours) => {
-    get().updateTask(taskId, { actualHours: hours });
-  },
-
   getByRequirement: (requirementId) => {
     return get().tasks.filter((t) => t.requirementId === requirementId);
   },