`pluralize` reads wrong key: `args["count"]` should be `args["value"]`

[BBC6BAE9]

Bug

PluralizeFunction.executeSync reads args['count'] but the spec defines the field as value, not count.

File: `packages/genui/lib/src/catalog/basic_functions.dart`

// current (wrong)
final Object? count = args['count'];

// should be
final Object? count = args['value'];

Spec reference

From `basic_catalog.json` (v0_9):

```json
"value": {
"description": "The numeric value used to determine the plural category."
}
```

The field is named `value` throughout the spec. There is no `count` field in `pluralize.args`.

Impact

Any `pluralize` call will always fall through to the `other` branch because `args['count']` is always `null`, regardless of the actual value passed by the agent.

Related

This is separate from the broader CLDR plural category issue tracked in google/A2UI#1385. That issue covers the missing `two`/`few`/`many` branches and the locale handling; this is a straightforward key name mismatch that makes the function completely non-functional today.