feat(worker): 实现集群限流与自适应负载

保留平台模型 RPM、TPM 和并发策略语义，增加 PostgreSQL 集群级租约、饱和候选重选和多平台自动负载，避免突发任务固定等待首个平台。\n\n新增 Worker 实时负载采样、自适应 active/heavy 容量、心跳与管理端指标，并扩展本地 acceptance runner，覆盖三 Worker、同模型三平台 2/4/6 并发和 48 个带图视频突发任务。\n\n验证：go test ./...、go vet ./...、PostgreSQL 跨 Store 集成测试、gofmt、bash -n、ShellCheck 及本地集群 provider-burst 验收通过；48/48 成功，无越限、重复提交、重复计费、重复回调或终态资源泄漏。

apps/api/internal/securityevents/metrics_test.go

@@ -25,6 +25,15 @@ func (m metricsSnapshot) PostgresPoolMetrics() store.PostgresPoolMetricsSnapshot
 	return m.pool
 }
 
+func (m metricsSnapshot) ListModelRateLimitStatuses(context.Context) ([]store.ModelRateLimitStatus, error) {
+	return []store.ModelRateLimitStatus{{
+		PlatformModelID: "platform-model-1",
+		RPM:             store.RateLimitMetricStatus{Ratio: .25},
+		TPM:             store.RateLimitMetricStatus{Ratio: .5},
+		Concurrent:      store.RateLimitMetricStatus{Ratio: .75},
+	}}, nil
+}
+
 func TestMetricsExposeBoundedOutcomesAndState(t *testing.T) {
 	metrics := &Metrics{}
 	metrics.ObserveReceipt("accepted", 20*time.Millisecond, 2)
@@ -34,6 +43,9 @@ func TestMetricsExposeBoundedOutcomesAndState(t *testing.T) {
 	metrics.ObserveIntrospection("failed")
 	metrics.ObserveJWKSRefreshFailure("ssf")
 	metrics.SetAsyncWorkerCapacity(96, 128, 96, true)
+	metrics.SetWorkerLoad(12, 3, 8, 2, 5, 1, "busy")
+	metrics.ObserveProviderQuotaWait("rpm")
+	metrics.ObserveProviderQuotaWait("tpm_total")
 	metrics.ObserveAsyncWorkerResize("success")
 	metrics.ObserveConcurrencyLeaseRenewal("success")
 	metrics.ObserveConcurrencyLeaseRenewal("lost")
@@ -65,6 +77,16 @@ func TestMetricsExposeBoundedOutcomesAndState(t *testing.T) {
 		`easyai_gateway_async_worker_capacity 96`,
 		`easyai_gateway_async_worker_desired_capacity 128`,
 		`easyai_gateway_async_worker_capacity_capped 1`,
+		`easyai_gateway_worker_safe_capacity 12`,
+		`easyai_gateway_worker_heavy_capacity 3`,
+		`easyai_gateway_worker_active_tasks 8`,
+		`easyai_gateway_worker_preparing_tasks 2`,
+		`easyai_gateway_worker_waiting_upstream_tasks 5`,
+		`easyai_gateway_worker_finalizing_tasks 1`,
+		`easyai_gateway_worker_pressure_state 1`,
+		`easyai_gateway_provider_quota_waits_total{outcome="rpm"} 1`,
+		`easyai_gateway_provider_quota_waits_total{outcome="tpm"} 1`,
+		`easyai_gateway_platform_model_rate_limit_utilization{platform_model_id="platform-model-1",metric="concurrent"} 0.750000`,
 		`easyai_gateway_async_worker_resizes_total{outcome="success"} 1`,
 		`easyai_gateway_concurrency_lease_renewals_total{outcome="success"} 1`,
 		`easyai_gateway_concurrency_lease_renewals_total{outcome="lost"} 1`,