feat(V0.2): 任务模块 —— 项目 / 列表与看板 / 列-状态绑定 / 一级子任务

需求 142 条 (T-*), 设计见 docs/V0.2/任务模块/

数据层:
- 新增 6 张表: Project / ProjectMember / BoardColumn / Task / TaskMember / TaskTag
- 看板列是实体(可增删改排序), Task.columnId 外键 RESTRICT 防误删列丢任务
- Task.status(todo/doing/done) 与 columnId 双落库, 二者正交

领域层 server/task-domain/ (唯一口径, 前后端不重复实现):
- resolveStatus: 列决定状态(只看目标列, 无拖出回退); 状态与列不匹配时按列序取第一个绑定该状态的列自动归位, 无匹配列则不移动; 子任务完全豁免
- retention: 逐列 6 档保留窗口(永不显示/当天/3天/本周/本月/永久显示), 以 doneAt 判定
- copyTask: 跨项目深拷贝, 人员按目标项目成员过滤并回报丢弃名单

接口: /api/projects, /api/columns, /api/tasks (均校验项目成员)

前端:
- 底部 Tab 插入「任务」, 位于「打卡」之后; 默认首页仍为打卡
- 列表视图(子任务缩进+折叠) / 看板视图(长按拖拽换列、拖到卡片降为子任务)
- 列设置(列管理+状态绑定+保留选项) / 任务详情(扩展信息卡片默认收起) / 成员管理
- 视图记忆与上次项目存设备端

已验证: 95 文件语法 0 错误、相对导入 0 缺失、领域逻辑用例全部通过

src/pages/task/ProjectView.jsx

@@ -0,0 +1,255 @@
+import { useCallback, useEffect, useMemo, useState } from 'react'
+import { DotLoading, Toast } from 'antd-mobile'
+import { projectApi, taskApi } from '../../api/task.js'
+import { filterVisible, msToNextBoundary } from './date.js'
+import { getViewMode, setViewMode } from './prefs.js'
+import ListView from './ListView.jsx'
+import BoardView from './BoardView.jsx'
+import ColumnSettings from './ColumnSettings.jsx'
+import TaskDetail from './TaskDetail.jsx'
+import ProjectMembers from './ProjectMembers.jsx'
+
+// 项目视图容器: 列表 / 看板 切换 + 数据装载 + 乐观更新
+export default function ProjectView({ projectId, onBack }) {
+  const [project, setProject] = useState(null)
+  const [tasks, setTasks] = useState(null)
+  const [columns, setColumns] = useState([])
+  const [err, setErr] = useState('')
+  const [mode, setMode] = useState(() => getViewMode(projectId) || 'list')
+  const [openTask, setOpenTask] = useState(null)
+  const [showColumns, setShowColumns] = useState(false)
+  const [showMembers, setShowMembers] = useState(false)
+  const [adding, setAdding] = useState(false)
+  const [tick, setTick] = useState(0) // 保留窗口重算触发
+
+  const load = useCallback(() => {
+    setErr('')
+    Promise.all([projectApi.detail(projectId), taskApi.list(projectId)])
+      .then(([p, t]) => {
+        setProject(p.item)
+        setColumns(p.item.columns || [])
+        setTasks(t.items || [])
+      })
+      .catch((e) => setErr(e.message))
+  }, [projectId])
+
+  useEffect(() => { setTasks(null); load() }, [load])
+
+  // 切换视图并记忆 (T-VW-02/03/06)
+  const switchMode = (next) => {
+    setMode(next)
+    setViewMode(projectId, next)
+  }
+
+  // 保留窗口到点重算 (T-EX-18)
+  useEffect(() => {
+    const options = (columns || []).map((c) => c.retention)
+    const near = options
+      .map((o) => msToNextBoundary(o))
+      .filter((v) => v != null)
+      .sort((a, b) => a - b)[0]
+    const t = setTimeout(() => setTick((v) => v + 1), near ? Math.min(near, 60_000) : 60_000)
+    return () => clearTimeout(t)
+  }, [columns, tick])
+
+  const visibleTasks = useMemo(
+    () => filterVisible(tasks || [], columns),
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    [tasks, columns, tick],
+  )
+
+  // ---- 乐观更新 ----
+  const patchTask = (id, patch) => setTasks((prev) => (prev || []).map((t) => {
+    if (t.id === id) return { ...t, ...patch }
+    const kids = (t.children || []).map((c) => (c.id === id ? { ...c, ...patch } : c))
+    return { ...t, children: kids }
+  }))
+
+  const replaceTask = (fresh) => setTasks((prev) => (prev || []).map((t) => (t.id === fresh.id ? fresh : t)))
+
+  /** 更新任务(列/状态/字段), 服务端裁决后以返回值为准 */
+  async function updateTask(id, patch) {
+    const snapshot = tasks
+    patchTask(id, patch)
+    try {
+      const r = await taskApi.update(id, patch)
+      replaceTask(r.item)
+      return r.item
+    } catch (e) {
+      setTasks(snapshot)
+      Toast.show({ content: e.message })
+      throw e
+    }
+  }
+
+  /** 勾选完成 / 取消完成 */
+  const toggleDone = (task) => updateTask(task.id, {
+    status: task.status === 'done' ? 'todo' : 'done',
+  })
+
+  /** 拖拽换列 (T-BD-04/07) */
+  const moveToColumn = async (task, columnId) => {
+    const col = columns.find((c) => c.id === columnId)
+    try {
+      await updateTask(task.id, { columnId })
+      const target = columns.find((c) => c.id === columnId)
+      if (target?.boundStatus && target.boundStatus !== task.status) {
+        Toast.show({ content: `已移入 ${col?.name}，状态改为「${target.boundStatus === 'done' ? '完成' : target.boundStatus === 'doing' ? '执行中' : '未开始'}」` })
+      } else {
+        Toast.show({ content: `已移入 ${col?.name}` })
+      }
+    } catch { /* 已回滚并提示 */ }
+  }
+
+  /** 改状态 (T-BD-14~16) */
+  const changeStatus = async (task, status) => {
+    try {
+      const fresh = await updateTask(task.id, { status })
+      const moved = fresh && fresh.columnId !== task.columnId
+      if (moved) {
+        const col = columns.find((c) => c.id === fresh.columnId)
+        Toast.show({ content: `已移至 ${col?.name || '目标列'}` })
+      }
+    } catch { /* ignore */ }
+  }
+
+  /** 拖拽降为子任务 (T-ST-12) */
+  const makeSubtask = async (task, parentId) => {
+    try {
+      await updateTask(task.id, { parentId })
+      // 成为子任务后不再作为顶层卡片出现
+      setTasks((prev) => (prev || []).filter((t) => t.id !== task.id))
+      Toast.show({ content: '已转为子任务' })
+      load()
+    } catch { /* 错误已提示 */ }
+  }
+
+  /** 新建任务 */
+  async function createTask(title, parentId = null) {
+    const t = String(title || '').trim()
+    if (!t) return
+    try {
+      await taskApi.create(projectId, { title: t, parentId })
+      setAdding(false)
+      load()
+    } catch (e) {
+      Toast.show({ content: e.message })
+    }
+  }
+
+  if (err) {
+    return (
+      <div className="page-with-navbar">
+        <div className="navbar-sub">
+          <span className="back" onClick={onBack}>‹</span>
+          <span className="title">任务</span>
+        </div>
+        <div className="empty">
+          <div className="ico err">!</div>
+          <p>{err}</p>
+          <div className="mini-btn solid" onClick={load}>重试</div>
+        </div>
+      </div>
+    )
+  }
+
+  if (!project || !tasks) {
+    return (
+      <div className="page-with-navbar">
+        <div className="navbar-sub">
+          <span className="back" onClick={onBack}>‹</span>
+          <span className="title">任务</span>
+        </div>
+        <div className="empty"><div className="ico">··</div><p>加载中…</p><DotLoading color="#1677ff" /></div>
+      </div>
+    )
+  }
+
+  return (
+    <div className="page-with-navbar">
+      <div className="navbar-sub">
+        <span className="back" onClick={onBack}>‹</span>
+        <span className="title">{project.name}</span>
+        <div className="right">
+          <span className="mini-btn" onClick={() => setShowMembers(true)}>成员</span>
+          <span className="mini-btn" onClick={() => setAdding((v) => !v)}>+ 新增</span>
+        </div>
+      </div>
+
+      <div className={`task-content${mode === 'board' ? ' is-board' : ''}`}>
+        <div className="pv-head">
+          <div className="seg">
+            <div className={mode === 'list' ? 'on' : ''} onClick={() => switchMode('list')}>列表</div>
+            <div className={mode === 'board' ? 'on' : ''} onClick={() => switchMode('board')}>看板</div>
+          </div>
+          <div className="right">
+            <span className="mini-btn grey" onClick={() => setShowColumns(true)}>列设置</span>
+          </div>
+        </div>
+
+        {adding && (
+          <div className="quick-add">
+            <input
+              className="inp"
+              autoFocus
+              placeholder="输入任务标题，回车创建"
+              onKeyDown={(e) => {
+                if (e.key === 'Enter') createTask(e.currentTarget.value)
+                if (e.key === 'Escape') setAdding(false)
+              }}
+            />
+          </div>
+        )}
+
+        {mode === 'list' ? (
+          <ListView
+            tasks={visibleTasks}
+            columns={columns}
+            onToggle={toggleDone}
+            onOpen={(t) => setOpenTask(t)}
+            onAddSub={(parent) => setOpenTask(parent)}
+          />
+        ) : (
+          <BoardView
+            tasks={visibleTasks}
+            columns={columns}
+            onMoveColumn={moveToColumn}
+            onMakeSubtask={makeSubtask}
+            onOpen={(t) => setOpenTask(t)}
+            onToggleSub={(c) => toggleDone(c)}
+            onToggle={(t) => toggleDone(t)}
+            onQuickAdd={() => { setAdding(true) }}
+          />
+        )}
+      </div>
+
+      {openTask && (
+        <TaskDetail
+          task={openTask}
+          columns={columns}
+          members={project.members || []}
+          onClose={() => setOpenTask(null)}
+          onSaved={() => { setOpenTask(null); load() }}
+          onChanged={load}
+        />
+      )}
+
+      {showColumns && (
+        <ColumnSettings
+          projectId={projectId}
+          columns={columns}
+          onClose={() => setShowColumns(false)}
+          onSaved={() => { setShowColumns(false); load() }}
+        />
+      )}
+
+      {showMembers && (
+        <ProjectMembers
+          project={project}
+          onClose={() => setShowMembers(false)}
+          onChanged={load}
+        />
+      )}
+    </div>
+  )
+}