feat: Add #[Throttle] Attribute for Rate Limiting

[techmahedy]

Adds a new #[Throttle] attribute for declarative rate limiting on controller methods, providing a modern alternative to docblock annotations and route-level rate limit parameters.

Currently, Doppar supports rate limiting through:

• Docblock annotations - @RateLimit 60/1
• Route attribute parameters - #[Route('/api/users', rateLimit: 60)]

This PR introduces a new #[Throttle] attribute for declarative rate limiting on controller methods.

Before (Docblock Annotation)

/**
 * Search API endpoint
 * 
 * @RateLimit 60/1
 */
#[Route('/api/search', methods: ['GET'])]
public function search(Request $request)
{
    return SearchService::query($request->input('q'));
}

Before (Route Attribute Parameter)

#[Route('/api/search', methods: ['GET'], rateLimit: 60, rateLimitDecay: 1)]
public function search(Request $request)
{
    return SearchService::query($request->input('q'));
}

Before (With Middleware)

#[Route('/api/search', methods: ['GET'], middleware: ['throttle:60,1'])]
public function search(Request $request)
{
    return SearchService::query($request->input('q'));
}

After (New #[Throttle] Attribute)

#[Route('/api/search', methods: ['GET'])]
#[Throttle(maxAttempts: 10, decayMinutes: 1)]
public function search(Request $request)
{
    return SearchService::query($request->input('q'));
}

Result: 10 requests per minute

In a future major version, we may deprecate docblock annotations and route parameters in favor of attributes.