(aws-cdk-lib/core): Size Type Transformation Results in Confusing Model Validation Error

### Describe the bug

When creating an EBS volume using `ServiceManagedVolume`, floating-point values for the `size` parameter are not automatically rounded, leading to CloudFormation deployment/validation failures that are difficult to debug. I believe the issue occurs because CloudFormation expects integer values for `SizeInGiB`, but floating-point numbers in the synthesized YAML are interpreted as strings.

The root cause here seemed to be that CDK generated a config value `SizeInGiB: 193.60000000000002` which the API model expected to be a number but the `193.60000000000002` value was treated as a string. Can this be an error or warning at build time instead?

## Workaround
Manually wrap the size calculation in `Math.ceil`:
```typescript
size: Size.gibibytes(Math.ceil(maxShardSizeGiB * 2 * 1.1))
```

## Additional Context
- This validation would improve developer experience by catching the issue earlier in the development cycle
- Similar validation might be useful for other numeric CloudFormation properties that require integers

### Regression Issue

- [ ] Select this option if this issue appears to be a regression.

### Last Known Working CDK Version

_No response_

### Expected Behavior

- Add validation (somewhere) in the CDK library to ensure sizes are integers
- Either:
1. Automatically round up floating-point values using `Math.ceil`
2. Throw a build-time validation error when non-integer values are provided

### Current Behavior

- Floating-point values for sizes (in this example, EBS volume sizes) are allowed and synthesized directly to CloudFormation
- This results in runtime deployment failures with cryptic error messages
- The error is not caught during build time or by `cfn-lint`

Error Message During Deployment
```
Resource handler returned message: "Model validation failed (#/VolumeConfigurations/0/ManagedEBSVolume/SizeInGiB: expected type: Integer, found: String)" ...
```

### Reproduction Steps

1. Create a `ServiceManagedVolume` with a calculated size that results in a floating-point number:

```typescript
const snapshotVolume = new ServiceManagedVolume(this, 'Volume', {
name: 'volume',
managedEBSVolume: {
size: Size.gibibytes(maxShardSizeGiB * 2 * 1.1), // Results in floating-point
// ...
},
});
```

2. Synthesize the stack
3. Deploy the stack
4. Observe CloudFormation deployment failure

## Generated CloudFormation
```yaml
VolumeConfigurations:
- ManagedEBSVolume:
Encrypted: true
FilesystemType: xfs
SizeInGiB: 193.60000000000002 # Should be an integer
```

### Possible Solution

_No response_

### Additional Information/Context

_No response_

### CDK CLI Version

2.1007.0

### Framework Version

2.139.0

### Node.js Version

NodeJS 18

### OS

Linux

### Language

TypeScript

### Language Version

_No response_

### Other information

_No response_

Begin at the ServiceManagedVolume managedEBSVolume size path and the Size.gibibytes API described in the report; reproduce the synthesized SizeInGiB value using the supplied calculation. Done means the chosen behavior—integer rounding or build-time validation—is defined and the floating-point input no longer reaches CloudFormation as an invalid SizeInGiB value.

Written by the indexing model from the issue text.