gen2-migration generate/assess fails with "Root resource not found for REST API" on APIs with >25 resources (missing pagination)

### How did you install the Amplify CLI?

NPM

### If applicable, what version of Node.js are you using?

22.22.3

### Amplify CLI Version

14.5.1

### What operating system are you using?

MacOs

### Did you make any manual changes to the cloud resources managed by Amplify? Please describe the changes made.

No manual changes made

### Describe the bug

When running `amplify gen2-migration generate` I receive the error:

```
→ Planning failed

🛑 Root resource not found for REST API ''
```

`fetchRestApiRootResourceId()` in packages/amplify-cli/src/commands/gen2-migration/_common/aws-fetcher.ts (lines 192–198) calls API Gateway's GetResourcesCommand exactly once with no pagination:

```
public async fetchRestApiRootResourceId(restApiId: string): Promise {
const { items } = await this.clients.apiGateway.send(new GetResourcesCommand({ restApiId }));
const root = items?.find((r) => r.path === '/');
if (!root?.id) {
throw new AmplifyError('RestApiResourceNotFoundError', {
message: `Root resource not found for REST API '${restApiId}'`,
```

GetResources paginates server-side (default page size 25, returns a position token) and item ordering isn't guaranteed to put / first. On any REST API with more than ~25 resources, / can land past page 1, this call never follows position, and generate/assess fails even though the API and its root resource are completely healthy.

### Expected behavior

`amplify gen2-migration generate` is able to run without error on large REST APIs

### Reproduction steps

Any Gen1 REST API category with 25+ Lambda-backed paths reproduces this. In our case (75 resources), root resource sits at position 66 in id order — confirmed via direct aws apigateway get-resources --no-paginate returning only 25 items, no root, with a position token present signaling more pages.

### Project Identifier

_No response_

### Log output

```
# Put your logs below this line

```

### Additional information

_No response_

### Before submitting, please confirm:

- [x] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.
- [x] I have removed any sensitive information from my code snippets and submission.

Start in packages/amplify-cli/src/commands/gen2-migration/_common/aws-fetcher.ts at fetchRestApiRootResourceId() and inspect the GetResourcesCommand response, including its position token. Reproduce with a REST API containing more than 25 resources, then verify that amplify gen2-migration generate or assess succeeds and locates the root resource on later pages.

Written by the indexing model from the issue text.