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/app/versions/[id]/page.tsx

@@ -8,7 +8,7 @@ import { useRequirementStore } from '@/stores/useRequirementStore';
 import { useOvertimeStore } from '@/stores/useOvertimeStore';
 import { getVersionDetail } from '@/lib/derive';
 import { STAGES } from '@/lib/stage';
-import { VersionStatus, VERSION_STATUS_LABEL, VERSION_STATUS_BG, getVersionDisplayStatus } from '@/lib/version-status';
+import { VersionStatus, VERSION_STATUS_LABEL, VERSION_STATUS_BG, getVersionDisplayStatus, calcVersionExecutionStatus, EXECUTION_STATUS_LABEL, EXECUTION_STATUS_COLOR } from '@/lib/version-status';
 import { CapsuleStages } from '@/components/version/CapsuleStages';
 import { MemberChips } from '@/components/version/MemberChips';
 import { HealthTrend, generateMockTrend } from '@/components/version/HealthTrend';
@@ -194,8 +194,17 @@ export default function VersionDetailPage() {
             const devTaskTodo = versionDevTasks.filter((t) => t.status === 'todo').length;
             const devTaskInProgress = versionDevTasks.filter((t) => t.status === 'in_progress').length;
             const devTaskBlocked = versionDevTasks.filter((t) => t.isBlocked).length;
-            const mockBugTotal = Math.max(Math.floor(versionReqs.length * 1.5), 2);
-            const mockBugOpen = Math.max(Math.floor(mockBugTotal * 0.3), 1);
+            const versionBugs = bugs.filter((b) => b.versionId === version.id);
+            const bugOpenCount = versionBugs.filter((b) => b.status === 'open' || b.status === 'fixing').length;
+
+            // 版本执行态推导
+            const versionTCs = testCases.filter((c) => c.versionId === version.id);
+            const executionStatus = calcVersionExecutionStatus({
+              manualStatus: version.status,
+              devTasks: versionDevTasks,
+              testCases: versionTCs,
+              bugs: versionBugs,
+            });
 
             return (
               <div className="space-y-4">
@@ -209,6 +218,9 @@ export default function VersionDetailPage() {
                   <span className={`text-[11px] px-2 py-0.5 rounded-full ${VERSION_STATUS_BG[version.status]}`}>
                     {getVersionDisplayStatus(version.status, version.currentStage)}
                   </span>
+                  <span className={`text-[11px] font-medium px-2 py-0.5 rounded-full ${EXECUTION_STATUS_COLOR[executionStatus]}`}>
+                    {EXECUTION_STATUS_LABEL[executionStatus]}
+                  </span>
                   <span className={`inline-flex items-center gap-1.5 text-[11px] font-semibold tabular-nums px-2 py-0.5 rounded-full ${healthLevel === 'critical' ? 'bg-red-50' : healthLevel === 'risk' ? 'bg-orange-50' : healthLevel === 'attention' ? 'bg-amber-50' : 'bg-emerald-50'} ${HEALTH_LEVEL_COLOR[healthLevel]}`}>
                     <span className={`h-1.5 w-1.5 rounded-full ${HEALTH_LEVEL_DOT[healthLevel]}`} />
                     {healthScore} {HEALTH_LEVEL_LABEL[healthLevel]}
@@ -230,7 +242,7 @@ export default function VersionDetailPage() {
                   <StatCard label="待开发" value={devTaskTodo} />
                   <StatCard label="开发中" value={devTaskInProgress} accent />
                   <StatCard label="阻塞中" value={devTaskBlocked} warn={devTaskBlocked > 0} />
-                  <StatCard label="参与人员" value={version.members?.length ?? 0} />
+                  <StatCard label="未关闭Bug" value={bugOpenCount} warn={bugOpenCount > 0} />
                 </div>
 
                 {/* 风险详情（胶囊条上方） */}
@@ -308,7 +320,7 @@ export default function VersionDetailPage() {
                   }
 
                   // 测试阶段进度由 TestCase 完成率驱动
-                  const versionTestCases = testCases.filter((c) => versionReqs.some((r) => r.id === c.requirementId));
+                  const versionTestCases = testCases.filter((c) => c.versionId === version.id);
                   if (versionTestCases.length > 0) {
                     const executed = versionTestCases.filter((c) => c.status === 'passed' || c.status === 'failed' || c.status === 'blocked').length;
                     const testPercent = Math.round((executed / versionTestCases.length) * 100);