fix(worker): 记住轮询间隔内的容量需求

异步视频任务在 River 轮询空档会释放本地 lease，采样瞬间可能观察不到已经触顶的领取需求，导致自适应容量长期停在初始值。本提交记录采样窗口内出现过的容量饱和，同时保持空闲 Worker 不盲目升容。\n\n移植时保留主线现有的单节点容量阶梯、请求下限和严格失败门禁，仅合入失败路径先记录并排空任务与回调、再删除模拟器资源的清理顺序，并补充脚本守卫。\n\n验证：go test ./... -count=1；go vet ./...；bash -n；ShellCheck；production-acceptance-script-test.sh。

apps/api/internal/workerload/controller_test.go

@@ -29,6 +29,43 @@ func TestControllerStartsConservativelyAndGrowsUnderSustainedDemand(t *testing.T
 	}
 }
 
+func TestControllerRemembersDemandAcrossShortPollingRuns(t *testing.T) {
+	controller := New(Config{Mode: ModeAdaptive, HardLimit: 8, InitialActive: 4, InitialHeavy: 4, HealthySamples: 2})
+	for range 2 {
+		leases := make([]*Lease, 0, 4)
+		for range 4 {
+			lease, ok := controller.TryStart()
+			if !ok {
+				t.Fatal("short polling task was not admitted")
+			}
+			leases = append(leases, lease)
+		}
+		for _, lease := range leases {
+			lease.Release()
+		}
+		controller.Observe(ResourceSample{
+			MemoryCurrentBytes: 30,
+			MemoryLimitBytes:   100,
+			CPUUtilization:     .3,
+			DBConnections:      3,
+			DBMaxConnections:   20,
+		})
+	}
+	if snapshot := controller.Snapshot(); snapshot.ActiveLimit != 5 || snapshot.SafeCapacity != 5 {
+		t.Fatalf("grown snapshot=%+v, want active=5 safe=5", snapshot)
+	}
+}
+
+func TestControllerDoesNotGrowWhileIdleWithoutDemand(t *testing.T) {
+	controller := New(Config{Mode: ModeAdaptive, HardLimit: 8, InitialActive: 4, InitialHeavy: 1, HealthySamples: 2})
+	for range 4 {
+		controller.Observe(ResourceSample{MemoryCurrentBytes: 20, MemoryLimitBytes: 100, CPUUtilization: .2})
+	}
+	if snapshot := controller.Snapshot(); snapshot.ActiveLimit != 4 {
+		t.Fatalf("idle snapshot=%+v, want active=4", snapshot)
+	}
+}
+
 func TestControllerBusyAndCriticalPressureReduceNewClaims(t *testing.T) {
 	controller := New(Config{Mode: ModeAdaptive, HardLimit: 16, InitialActive: 8, InitialHeavy: 2})
 	busy := controller.Observe(ResourceSample{MemoryCurrentBytes: 80, MemoryLimitBytes: 100})