events: EventPattern should validate against empty arrays at synth time

### Describe the bug

When an `EventPattern` property (such as `detailType`, `source`, `account`, etc.) is set to an empty array `[]`, CDK synthesizes the template without any error. However, EventBridge rejects empty arrays in event patterns, causing a CloudFormation deployment failure:

```
Resource handler returned message: "Event pattern is not valid. Reason: Empty arrays are not allowed
at [Source: (String)"{"detail-type":[],"source":["example.source"],"account":["123456789012"]}";
line: 1, column: 18] (Service: EventBridge, Status Code: 400, ...)
```

CDK should validate that no `EventPattern` field is set to an empty array during synthesis, providing a clear error message before deployment.

### Expected Behavior

`cdk synth` should throw a validation error when any `EventPattern` field is an empty array, e.g.:

```
Error: Invalid event pattern: 'detailType' must be a non-empty array
```

### Current Behavior

CDK synthesizes the template successfully. The error is only discovered at deploy time when CloudFormation calls the EventBridge PutRule API.

### Reproduction Steps

```ts
import * as events from 'aws-cdk-lib/aws-events';

const rule = new events.Rule(this, 'Rule', {
eventPattern: {
source: ['my.source'],
detailType: [], // <-- empty array, should be caught at synth time
},
});
```

Running `cdk synth` succeeds. Running `cdk deploy` fails with the EventBridge validation error above.

### Additional Information/Context

- The `Match` class already validates for non-empty collections (e.g., `Match.anythingBut()` throws if given an empty list), so there's precedent for this kind of validation in the same module.
- The fix would be in `renderEventPattern()` in `packages/aws-cdk-lib/aws-events/lib/util.ts` — adding a check that no array value is empty before rendering the pattern.
- All array-typed fields on the `EventPattern` interface should be validated: `account`, `detailType`, `detail`, `id`, `region`, `resources`, `source`, `time`, `version`.

### CDK CLI Version

2.1104.0

### Framework Version

aws-cdk-lib 2.236.0

### Node.js Version

24.13.0

### OS

macOS (Darwin 25.2.0)

### Language

TypeScript

### Language Version

5.9.3

### Other information

_No response_

Read packages/aws-cdk-lib/aws-events/lib/util.ts and start at renderEventPattern(). Use the existing Match validation precedent, then verify that every listed array-typed EventPattern field rejects [] during synthesis with the stated error. Done means empty arrays cannot reach the rendered event pattern.

Written by the indexing model from the issue text.