refactor: 压平数据模型 — 版本为执行主线，需求降为语义标签

核心改动：
- TestCase 主归属 versionId，requirementId 改为可选语义标签
- Bug 新增 versionId（直接挂版本）+ requirementId（可选追溯）
- 新增 calcVersionExecutionStatus() 版本执行态推导函数
  规则：DevTask全部提测→已提测，TestCase全部通过+Bug全关→可发布
- 概览页展示推导出的执行态标签
- BugTab 改为直接 versionId 查询（不再走 testCase→req 链路）
- 统计卡片"参与人员"替换为"未关闭Bug"

心智模型：
  版本（执行线）→ DevTask/TestCase/Bug
  需求（语义线）→ 解释为什么做，不驱动流程

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

apps/web/components/test-case/TestCaseCreateModal.tsx

@@ -9,11 +9,12 @@ import { useAuthStore } from '@/stores/useAuthStore';
 import type { Priority } from '@/lib/derive';
 
 interface Props {
+  versionId: string;
   requirementIds: string[];
   onClose: () => void;
 }
 
-export function TestCaseCreateModal({ requirementIds, onClose }: Props) {
+export function TestCaseCreateModal({ versionId, requirementIds, onClose }: Props) {
   const { createTestCase } = useTestCaseStore();
   const { requirements } = useRequirementStore();
   const { members } = useMemberStore();
@@ -30,12 +31,13 @@ export function TestCaseCreateModal({ requirementIds, onClose }: Props) {
   const [assigneeId, setAssigneeId] = useState(user?.name || '');
   const [description, setDescription] = useState('');
 
-  const canSubmit = title.trim() && requirementId;
+  const canSubmit = title.trim();
 
   const handleSubmit = () => {
     if (!canSubmit) return;
     createTestCase({
-      requirementId,
+      versionId,
+      requirementId: requirementId || undefined,
       title: title.trim(),
       description: description.trim() || undefined,
       priority,
@@ -58,8 +60,9 @@ export function TestCaseCreateModal({ requirementIds, onClose }: Props) {
             <input value={title} onChange={(e) => setTitle(e.target.value)} className="h-9 w-full rounded-lg border border-[var(--line)] bg-[var(--bg)] px-3 text-[13px] focus:border-[var(--accent)] focus:outline-none" placeholder="例如：正常排班" />
           </div>
           <div>
-            <label className="block text-[12px] text-[var(--ink-soft)] mb-1">所属需求 *</label>
+            <label className="block text-[12px] text-[var(--ink-soft)] mb-1">关联需求（可选）</label>
             <select value={requirementId} onChange={(e) => { setRequirementId(e.target.value); const r = versionReqs.find((x) => x.id === e.target.value); if (r) setPriority(r.priority); }} className="h-9 w-full rounded-lg border border-[var(--line)] bg-[var(--bg)] px-3 text-[13px] focus:border-[var(--accent)] focus:outline-none">
+              <option value="">不关联需求</option>
               {versionReqs.map((r) => <option key={r.id} value={r.id}>{r.code} {r.title}</option>)}
             </select>
           </div>

apps/web/components/test-case/TestCaseTab.tsx

@@ -29,7 +29,7 @@ export function TestCaseTab({ versionId, requirementIds }: Props) {
   useEffect(() => { fetchBugs(); }, [fetchBugs]);
 
   const versionCases = useMemo(
-    () => testCases.filter((c) => requirementIds.includes(c.requirementId)),
+    () => testCases.filter((c) => c.versionId === versionId),
     [testCases, requirementIds],
   );
 
@@ -52,13 +52,14 @@ export function TestCaseTab({ versionId, requirementIds }: Props) {
   const [selectedCaseId, setSelectedCaseId] = useState<string | null>(null);
   const [bugForCaseId, setBugForCaseId] = useState<string | null>(null);
 
-  // 按需求分组
+  // 按需求分组（无需求的归为"通用"）
   const groupedByReq = useMemo(() => {
     const map = new Map<string, typeof paged>();
     for (const c of paged) {
-      const list = map.get(c.requirementId) || [];
+      const key = c.requirementId || '__none__';
+      const list = map.get(key) || [];
       list.push(c);
-      map.set(c.requirementId, list);
+      map.set(key, list);
     }
     return map;
   }, [paged]);
@@ -133,7 +134,7 @@ export function TestCaseTab({ versionId, requirementIds }: Props) {
 
       {total > 20 && <Pagination total={total} page={page} pageSize={pageSize} onChange={setPage} onPageSizeChange={setPageSize} />}
 
-      {showCreate && <TestCaseCreateModal requirementIds={requirementIds} onClose={() => setShowCreate(false)} />}
+      {showCreate && <TestCaseCreateModal versionId={versionId} requirementIds={requirementIds} onClose={() => setShowCreate(false)} />}
       {selectedCaseId && <TestCaseDetailDrawer testCaseId={selectedCaseId} onClose={() => setSelectedCaseId(null)} onCreateBug={(id) => { setBugForCaseId(id); }} />}
       {bugForCaseId && <BugCreateModal testCaseId={bugForCaseId} onClose={() => setBugForCaseId(null)} />}
     </div>