Incorrect Claude 4.x model names on AI docs pages

## Problem

The Amplify docs AI pages use `Claude [VERSION] [SIZE]` format for Claude 4+ models (e.g., `Claude 4.5 Haiku`), but the actual `a.ai.model()` accepted strings use `Claude [SIZE] [VERSION]` (e.g., `Claude Haiku 4.5`).

This matches the Bedrock naming convention change for post-4 models ([Bedrock model cards](https://docs.aws.amazon.com/bedrock/latest/userguide/model-cards.html)).

## Source of truth

[`ModelType.ts`](https://github.com/aws-amplify/amplify-data/blob/0502b8ef59af513a318093f2e8bf1bb4f988cea4/packages/data-schema/src/ai/ModelType.ts#L6) defines the accepted strings:

```typescript
// 3.x — VERSION then SIZE (correct in docs)
'Claude 3.5 Haiku'
'Claude 3.5 Sonnet'

// 4+ — SIZE then VERSION (wrong in docs)
'Claude Opus 4'
'Claude Sonnet 4'
'Claude Haiku 4.5'
'Claude Sonnet 4.5'
'Claude Opus 4.5'
'Claude Sonnet 4.6'
'Claude Opus 4.6'
```

## Affected pages

- https://docs.amplify.aws/react/ai/set-up-ai/
- https://docs.amplify.aws/react/ai/concepts/
- Any page showing `a.ai.model()` examples

## Expected

Docs should show `Claude Haiku 4.5` (not `Claude 4.5 Haiku`) to match the code and Bedrock naming.

Users copying from docs will get a TypeScript compile error since the string doesn't match `keyof typeof supportedModelsLookup`.