feat(test-case+bug): 测试用例模块 + Bug 模块完整实现

需求验收体系：
- 测试用例：五态状态机（待执行/执行中/通过/失败/阻塞）
- Bug：六态状态机（待修复/修复中/已修复/验证中/已关闭/已拒绝）
- Bug 通过测试用例间接关联需求（不冗余存版本）
- Bug 默认修复人 = 关联需求的开发任务负责人
- 测试进度 = 已执行用例/总用例, 通过率 = 通过/已执行

UI:
- 版本详情页新增"测试用例" Tab + "BUG" Tab
- 测试用例：统计栏+筛选+按需求分组列表+详情抽屉+提BUG入口
- Bug：统计栏+筛选+列表+详情抽屉（链式跳转用例→需求）
- 概览胶囊"测试"阶段进度联动
- "与我相关"新增测试用例/Bug分组

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

apps/web/stores/useTestCaseStore.ts

@@ -0,0 +1,95 @@
+'use client';
+import { create } from 'zustand';
+import type { TestCase, TestCaseStatus } from '@/lib/test-case';
+import { canTcTransition, generateCaseNo } from '@/lib/test-case';
+
+const STORAGE_KEY = 'ftb_test_cases_v1';
+
+function saveLocal(items: TestCase[]) {
+  try { localStorage.setItem(STORAGE_KEY, JSON.stringify(items)); } catch {}
+}
+
+function loadLocal(): TestCase[] | null {
+  try {
+    const raw = localStorage.getItem(STORAGE_KEY);
+    if (raw) return JSON.parse(raw);
+  } catch {}
+  return null;
+}
+
+interface TestCaseState {
+  testCases: TestCase[];
+  fetchTestCases: () => void;
+  createTestCase: (data: Omit<TestCase, 'id' | 'caseNo' | 'createdAt' | 'updatedAt' | 'status'>) => TestCase;
+  updateTestCase: (id: string, data: Partial<TestCase>) => void;
+  deleteTestCase: (id: string) => void;
+  changeStatus: (id: string, to: TestCaseStatus, extra?: { failReason?: string; blockReason?: string }) => { ok: boolean; message?: string };
+  getByRequirement: (reqId: string) => TestCase[];
+  getByAssignee: (assigneeId: string) => TestCase[];
+}
+
+export const useTestCaseStore = create<TestCaseState>((set, get) => ({
+  testCases: [],
+
+  fetchTestCases: () => {
+    const cached = loadLocal();
+    if (cached) set({ testCases: cached });
+  },
+
+  createTestCase: (data) => {
+    const list = get().testCases;
+    const now = new Date().toISOString();
+    const tc: TestCase = {
+      ...data,
+      id: `tc-${Date.now()}`,
+      caseNo: generateCaseNo(list),
+      status: 'pending',
+      createdAt: now,
+      updatedAt: now,
+    };
+    const updated = [...list, tc];
+    set({ testCases: updated });
+    saveLocal(updated);
+    return tc;
+  },
+
+  updateTestCase: (id, data) => {
+    const updated = get().testCases.map((c) =>
+      c.id === id ? { ...c, ...data, updatedAt: new Date().toISOString() } : c,
+    );
+    set({ testCases: updated });
+    saveLocal(updated);
+  },
+
+  deleteTestCase: (id) => {
+    const updated = get().testCases.filter((c) => c.id !== id);
+    set({ testCases: updated });
+    saveLocal(updated);
+  },
+
+  changeStatus: (id, to, extra) => {
+    const tc = get().testCases.find((c) => c.id === id);
+    if (!tc) return { ok: false, message: '用例不存在' };
+    if (!canTcTransition(tc.status, to)) {
+      return { ok: false, message: `不允许从「${tc.status}」流转到「${to}」` };
+    }
+    const today = new Date().toISOString().slice(0, 10);
+    const patch: Partial<TestCase> = { status: to };
+    if (to === 'running' || to === 'passed' || to === 'failed' || to === 'blocked') {
+      patch.executedAt = today;
+    }
+    if (to === 'failed' && extra?.failReason) patch.failReason = extra.failReason;
+    if (to === 'blocked' && extra?.blockReason) patch.blockReason = extra.blockReason;
+    if (to === 'running') { patch.failReason = undefined; patch.blockReason = undefined; }
+    get().updateTestCase(id, patch);
+    return { ok: true };
+  },
+
+  getByRequirement: (reqId) => {
+    return get().testCases.filter((c) => c.requirementId === reqId);
+  },
+
+  getByAssignee: (assigneeId) => {
+    return get().testCases.filter((c) => c.assigneeId === assigneeId);
+  },
+}));