feat(acceptance): 建立同构验收与弹性容量体系

实现本地三节点 K3s 同构环境、脱敏生产快照、Gemini 图片和多参考图视频协议模拟、统一验收报告及故障注入。\n\n新增 Worker 容量控制器、资源与连接预算、任务恢复保护，并将生产验收拆分为 validation 执行和人工 CAS 放量。\n\n验证包括 Go 全量测试、PostgreSQL HTTP 集成测试、go vet、OpenAPI、ShellCheck、前端检查、迁移及发布脚本测试。

apps/api/internal/store/leadership.go

@@ -14,6 +14,7 @@ const leadershipReleaseTimeout = 5 * time.Second
 const (
 	identityCoordinatorLeadershipKey    = "easyai-gateway-identity-coordinator"
 	securityEventHeartbeatLeadershipKey = "easyai-gateway-security-event-heartbeat"
+	capacityControllerLeadershipKey     = "easyai-gateway-capacity-controller"
 )
 
 // Leadership holds a PostgreSQL session advisory lock. Callers must keep the
@@ -37,6 +38,10 @@ func (s *Store) TryAcquireSecurityEventHeartbeatLeadership(ctx context.Context)
 	return s.tryAcquireLeadership(ctx, securityEventHeartbeatLeadershipKey)
 }
 
+func (s *Store) TryAcquireCapacityControllerLeadership(ctx context.Context) (Leadership, bool, error) {
+	return s.tryAcquireLeadership(ctx, capacityControllerLeadershipKey)
+}
+
 func (s *Store) tryAcquireLeadership(ctx context.Context, key string) (Leadership, bool, error) {
 	conn, err := s.pool.Acquire(ctx)
 	if err != nil {