events: using fromObject does not maintain keys in inputTransformer

### Describe the bug

creating a rule target using fromObject does not preserve the key names, but rather generates a key from the values in the input paths. using L1 CfnRule works as expected

```
import * as cdk from "aws-cdk-lib";
import * as events from "aws-cdk-lib/aws-events";
import * as targets from "aws-cdk-lib/aws-events-targets";
import * as sqs from "aws-cdk-lib/aws-sqs";
import { Construct } from "constructs";

export class BugfixEventbridgeStack extends cdk.Stack {
constructor(scope: Construct, id: string, props?: cdk.StackProps) {
super(scope, id, props);

let inputPathsMap = {
myName: events.EventField.fromPath("$.detail.name"),
myUUID: events.EventField.fromPath("$.detail.uuid"),
};

const queue = new sqs.Queue(this, "myQueue");

new events.CfnRule(this, "myCFNrule", {
name: "myCFNrule",
eventPattern: {
source: ["aws.ec2"]
},
state: "ENABLED",
targets: [
{
arn: queue.queueArn,
id: "shared-sqs-cfn",
inputTransformer: {
inputTemplate: JSON.stringify(inputPathsMap),
inputPathsMap: inputPathsMap,
},
},
],
});

const cdkRule = new events.Rule(this, "myCDKrule", {
ruleName: 'myCDKrule',
eventPattern: {
source: ["aws.ec2"]
}
});
cdkRule.addTarget(new targets.SqsQueue(queue, {
message: events.RuleTargetInput.fromObject(inputPathsMap)
}));

}
}

```

### Regression Issue

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

### Last Known Working CDK Version

_No response_

### Expected Behavior

InputPathsMap is the same for myCFNrule and myCDKrule, using the key/value pairs provided in inputPathsMap

### Current Behavior

using the L2 construct (fromObject), keys provided in inputPathsMap are overwritten with system-generated keys. from cdk synth:

```
myCFNrule:
Type: AWS::Events::Rule
Properties:
EventPattern:
source:
- aws.ec2
Name: myCFNrule
State: ENABLED
Targets:
- Arn:
Fn::GetAtt:
- myQueue4FDFF71C
- Arn
Id: shared-sqs-cfn
InputTransformer:
InputPathsMap:
myName: $.detail.name
myUUID: $.detail.uuid
InputTemplate: '{"myName":"$.detail.name","myUUID":"$.detail.uuid"}'
Metadata:
aws:cdk:path: BugfixEventbridgeStack/myCFNrule
myCDKruleB18813AA:
Type: AWS::Events::Rule
Properties:
EventPattern:
source:
- aws.ec2
Name: myCDKrule
State: ENABLED
Targets:
- Arn:
Fn::GetAtt:
- myQueue4FDFF71C
- Arn
Id: Target0
InputTransformer:
InputPathsMap:
detail-name: $.detail.name
detail-uuid: $.detail.uuid
InputTemplate: '{"myName":,"myUUID":}'
Metadata:
aws:cdk:path: BugfixEventbridgeStack/myCDKrule/Resource

```

### Reproduction Steps

run the code provided in issue description

### Possible Solution

_No response_

### Additional Information/Context

same issue occurs whether using events.RuleTargetInput.fromObject(inputPathsMap) or events.RuleTargetInput.fromText(JSON.stringify(inputPathsMap))

### CDK CLI Version

2.1004.0 (build f0ad96e)

### Framework Version

_No response_

### Node.js Version

v23.9.0

### OS

Windows

### Language

TypeScript

### Language Version

typescript@5.6.3, aws-cdk-lib@2.181.1

### Other information

_No response_

Start by running the TypeScript reproduction and comparing the synthesized InputTransformer for RuleTargetInput.fromObject and fromText with the CfnRule output. Trace the events.RuleTargetInput and targets.SqsQueue entry points, then add or update coverage so the provided inputPathsMap key names are preserved and the synthesized template matches the expected mapping.

Written by the indexing model from the issue text.