Add action responses and improved custom client headers

[victorycodedev]

Summary

This release improves account creation workflows and custom HTTP client support.

Changes

• Added ActionResponse for account and account replica creation
• Added helpers to detect 201 Created vs 202 Accepted
• Added retryAfter(), shouldRetry(), id(), and state() helpers
• Updated accounts()->create() to return ActionResponse
• Updated accountReplicas()->createReplica() to return ActionResponse
• Ensured SDK authentication headers are applied even when using a custom Guzzle client
• Avoided forcing JSON Content-Type on file uploads
• Updated README examples for account and replica creation
• Expanded Pest test coverage

Example

$response = $metaapi->accounts()->create([
    'login' => '123456',
    'password' => 'password',
    'name' => 'Main account',
    'server' => 'ICMarketsSC-Demo',
    'platform' => 'mt5',
    'magic' => 123456,
    'type' => 'cloud-g2',
]);

if ($response->isCreated()) {
    echo $response->id();
}

if ($response->isAccepted()) {
    echo $response->retryAfter();
}