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/lib/test-case.ts

@@ -0,0 +1,69 @@
+import type { Priority } from './derive';
+
+export type TestCaseStatus = 'pending' | 'running' | 'passed' | 'failed' | 'blocked';
+
+export interface TestCase {
+  id: string;
+  caseNo: string;
+  requirementId: string;
+  title: string;
+  description?: string;
+  priority: Priority;
+  assigneeId?: string;
+  status: TestCaseStatus;
+  executedAt?: string;
+  executedBy?: string;
+  failReason?: string;
+  blockReason?: string;
+  createdBy: string;
+  createdAt: string;
+  updatedAt: string;
+}
+
+export const TEST_CASE_STATUS_LABEL: Record<TestCaseStatus, string> = {
+  pending: '待执行',
+  running: '执行中',
+  passed: '通过',
+  failed: '失败',
+  blocked: '阻塞',
+};
+
+export const TEST_CASE_STATUS_COLOR: Record<TestCaseStatus, string> = {
+  pending: 'bg-zinc-100 text-zinc-600',
+  running: 'bg-blue-50 text-blue-600',
+  passed: 'bg-emerald-50 text-emerald-600',
+  failed: 'bg-red-50 text-red-600',
+  blocked: 'bg-orange-50 text-orange-600',
+};
+
+export const TC_ALLOWED_TRANSITIONS: Record<TestCaseStatus, TestCaseStatus[]> = {
+  pending: ['running'],
+  running: ['passed', 'failed', 'blocked'],
+  passed: ['running'],
+  failed: ['running'],
+  blocked: ['running'],
+};
+
+export function canTcTransition(from: TestCaseStatus, to: TestCaseStatus): boolean {
+  return TC_ALLOWED_TRANSITIONS[from].includes(to);
+}
+
+export function generateCaseNo(existingCases: TestCase[]): string {
+  const maxNum = existingCases.reduce((max, c) => {
+    const num = parseInt(c.caseNo.replace('TC-', ''), 10);
+    return isNaN(num) ? max : Math.max(max, num);
+  }, 0);
+  return `TC-${String(maxNum + 1).padStart(3, '0')}`;
+}
+
+export function calcTestProgress(cases: TestCase[]): { total: number; executed: number; passed: number; failed: number; blocked: number; passRate: number; completionRate: number } {
+  const total = cases.length;
+  if (total === 0) return { total: 0, executed: 0, passed: 0, failed: 0, blocked: 0, passRate: 0, completionRate: 0 };
+  const passed = cases.filter((c) => c.status === 'passed').length;
+  const failed = cases.filter((c) => c.status === 'failed').length;
+  const blocked = cases.filter((c) => c.status === 'blocked').length;
+  const executed = passed + failed + blocked;
+  const passRate = (passed + failed) > 0 ? Math.round((passed / (passed + failed)) * 100) : 0;
+  const completionRate = Math.round((executed / total) * 100);
+  return { total, executed, passed, failed, blocked, passRate, completionRate };
+}