Add missing types to Endpoints\Indexes

[Strift]

The Indexes endpoint class requires updates to Method signatures and PHPDoc to support stricter typing.

File: src/Endpoints/Indexes.php

Action:

• newInstance(array $attributes): Add specific PHPDoc array shape.
• fill(array $attributes): Add specific PHPDoc array shape.
• create(string $uid, array $options = []): Add PHPDoc @param array{primaryKey?: string} $options.
• update(array $body): Add PHPDoc defining the expected shape of $body.
• rawSearch(?string $query, array $searchParams = []): Add PHPDoc defining the return array shape.
• stats(): Add explicit return type (e.g., IndexStats object) or specific PHPDoc.
• getSettings(): Add PHPDoc for return array shape.
• updateSettings($settings): Add type hint updateSettings(array $settings) (or accept a Settings object).