(aws-ecs): support configurable ECS deployment circuit breaker settings

## Describe the feature

Amazon ECS recently added support for configurable deployment circuit breaker settings. The CloudFormation resource specification now includes new `AWS::ECS::Service.DeploymentCircuitBreaker` properties:

- `ResetOnHealthyTask`
- `ThresholdConfiguration`

and a new nested `AWS::ECS::Service.ThresholdConfiguration` property type with:

- `Type`
- `Value`

The CDK `aws-ecs` L2 `DeploymentCircuitBreaker` interface currently only exposes:

```ts
export interface DeploymentCircuitBreaker {
readonly enable?: boolean;
readonly rollback?: boolean;
}
```

`CfnService.DeploymentCircuitBreakerProperty` on current `main` also only includes `enable` and `rollback`, so the generated L1 is stale relative to the latest CloudFormation resource specification.

## Use Case

ECS users need to tune when a rolling deployment is considered failed. The new ECS feature allows users to:

- use a fixed failure count or desired-count percentage as the failure threshold
- choose whether failures are counted consecutively by resetting on a healthy task, or cumulatively across the deployment

This is useful for services with expected startup churn, slow initialization, or different rollback tolerances between development, staging, and production.

## Proposed Solution

Update the generated L1 for `AWS::ECS::Service.DeploymentCircuitBreaker` so `CfnService.DeploymentCircuitBreakerProperty` includes:

```ts
readonly resetOnHealthyTask?: boolean | cdk.IResolvable;
readonly thresholdConfiguration?: CfnService.ThresholdConfigurationProperty | cdk.IResolvable;
```

and add the generated `CfnService.ThresholdConfigurationProperty` with:

```ts
readonly type: string;
readonly value: number;
```

Then add L2 support in `packages/aws-cdk-lib/aws-ecs/lib/base/base-service.ts`, for example:

```ts
export interface DeploymentCircuitBreaker {
/**
* Whether to enable the deployment circuit breaker logic.
*
* @default true
*/
readonly enable?: boolean;

/**
* Whether to configure Amazon ECS to roll back the service if a service deployment fails.
*
* @default false
*/
readonly rollback?: boolean;

/**
* Whether the deployment circuit breaker resets its failure count when a task reaches a healthy state.
*
* @default - Amazon ECS default
*/
readonly resetOnHealthyTask?: boolean;

/**
* The failure threshold configuration used by the deployment circuit breaker.
*
* @default - Amazon ECS defaults to BOUNDED_PERCENT with value 50
*/
readonly thresholdConfiguration?: DeploymentCircuitBreakerThresholdConfiguration;
}
```

with a jsii-compatible threshold configuration type, likely something like:

```ts
export interface DeploymentCircuitBreakerThresholdConfiguration {
/**
* How Amazon ECS uses `value` to calculate the failure threshold.
*/
readonly type: DeploymentCircuitBreakerThresholdType;

/**
* The integer Amazon ECS uses to calculate the failure threshold.
*/
readonly value: number;
}

export enum DeploymentCircuitBreakerThresholdType {
COUNT = 'COUNT',
BOUNDED_PERCENT = 'BOUNDED_PERCENT',
UNBOUNDED_PERCENT = 'UNBOUNDED_PERCENT',
}
```

and synthesize:

```ts
deploymentCircuitBreaker: props.circuitBreaker ? {
enable: props.circuitBreaker.enable ?? true,
rollback: props.circuitBreaker.rollback ?? false,
resetOnHealthyTask: props.circuitBreaker.resetOnHealthyTask,
thresholdConfiguration: props.circuitBreaker.thresholdConfiguration,
} : undefined,
```

Unit tests should verify that the new L2 props synthesize to:

```json
{
"DeploymentCircuitBreaker": {
"Enable": true,
"Rollback": true,
"ResetOnHealthyTask": true,
"ThresholdConfiguration": {
"Type": "COUNT",
"Value": 10
}
}
}
```

and that omitting the new optional props preserves the current synthesized output.

## Other Information

AWS announcement:
- https://aws.amazon.com/about-aws/whats-new/2026/07/amazon-ecs-circuit-breaker-settings/

ECS docs:
- https://docs.aws.amazon.com/AmazonECS/latest/developerguide/deployment-circuit-breaker.html

CloudFormation docs:
- https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-ecs-service-deploymentcircuitbreaker.html
- https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-properties-ecs-service-thresholdconfiguration.html

## Acknowledgements

- [x] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

## AWS CDK Library version

2.261.0

## AWS CDK CLI version

N/A

## Environment details

N/A

Start by inspecting the generated CfnService.DeploymentCircuitBreakerProperty and the L2 types and synthesis logic in packages/aws-cdk-lib/aws-ecs/lib/base/base-service.ts. Locate the existing aws-ecs unit tests and verify that the new circuit-breaker properties synthesize correctly while omitting them preserves the current output.

Written by the indexing model from the issue text.