Improved PHPDoc Return Types for Eloquent's Original Attribute Methods

[clementbirkle]

This PR enhances the type information in PHPDoc blocks for three methods that retrieve original attributes:

• getOriginal()
• getOriginalWithoutRewindingModel()
• getRawOriginal()

Changes

Replaced the generic @return mixed|array with a more precise conditional return type: @return ($key is null ? array<string, mixed> : mixed)

This better communicates that:

• When no key is provided, these methods return an array of all original attributes
• When a key is provided, they return a mixed value for that specific attribute

Benefits

• Improved static analysis capabilities
• Better IDE type hinting and autocompletion
• More accurate documentation for developers

No functional changes were made to the implementation.