feat: Add #[UsePolicy] attribute for declarative policy binding

[binaryfire]

Summary

This PR ports Laravel's #[UsePolicy] attribute to Hypervel, allowing models to declare their authorization policy class using a PHP attribute instead of manual registration.

Changes

New Files

• src/core/src/Database/Eloquent/Attributes/UsePolicy.php - The attribute class that can be applied to model classes to declare their policy

Modified Files

• src/auth/src/Access/Gate.php - Added getPolicyFromAttribute() method and updated getPolicyFor() to check for the attribute

Test Files

• tests/Auth/Access/GateTest.php - Added 5 new test cases
• tests/Auth/Stub/DummyWithUsePolicy.php - Test model with attribute
• tests/Auth/Stub/DummyWithUsePolicyPolicy.php - Test policy class
• tests/Auth/Stub/DummyWithoutUsePolicy.php - Test model without attribute
• tests/Auth/Stub/SubDummyWithUsePolicy.php - Test subclass with attribute

Usage

use Hypervel\Database\Eloquent\Attributes\UsePolicy;

#[UsePolicy(PostPolicy::class)]
class Post extends Model
{
    // ...
}

The Gate will now automatically resolve PostPolicy when authorizing actions on Post models:

Gate::authorize('update', $post); // Uses PostPolicy

Policy Resolution Order

1. Explicit registration - Gate::policy(Post::class, PostPolicy::class) takes precedence
2. #[UsePolicy] attribute - Checked if no explicit policy is registered
3. Subclass fallback - Falls back to parent class policies if no attribute found

Key Differences from #[ObservedBy] / #[ScopedBy]

Aspect	ObservedBy / ScopedBy	UsePolicy
Implementation location	Model traits	Gate class
Resolution mechanism	Model boots and registers	Gate reads at runtime
Inheritance/trait support	Collects from parents + traits	Single class only
Repeatable	Yes	No
Pivot model changes needed	Yes	No

The #[UsePolicy] attribute is simpler because the Gate reads the attribute via reflection at authorization time - no model trait or boot mechanism is required.

Test Plan

• Policy can be resolved from #[UsePolicy] attribute
• Works with object instances, not just class names
• Explicit policy registration takes precedence over attribute
• Attribute takes precedence over subclass fallback
• Returns null for classes without the attribute