Fix Go doc-comment association for maxPages and getList

## Summary

Move the `maxPages` constant and its documentation above the `getList` doc comment in `internal/api/client.go`.

## Rationale

The current declaration is positioned between the `getList` documentation and the function. As a result, Go documentation associates the trailing paragraph with `maxPages`, while `getList` no longer has a correctly attached doc comment.

## Affected area

- `internal/api/client.go`
- `maxPages`
- `(*Client).getList`

## Required change

Reorder the declarations so that:
1. `maxPages` is immediately preceded by its own `// maxPages ...` comment.
2. The `// getList ...` comment immediately precedes `func (c *Client) getList(...)`.

## Acceptance criteria

- `maxPages` and `getList` each have a correctly attached Go doc comment.
- The change is documentation/declaration ordering only; pagination behaviour remains unchanged.

## Backlinks

- Deferred from PR #43: https://github.com/Flagsmith/flagsmith-cli/pull/43
- Review comment: https://github.com/Flagsmith/flagsmith-cli/pull/43#discussion_r3666673361
- Requested by: @khvn26