Proposal: Add Route attribute for HTTP endpoints

[dbuhonov]

This PR proposes a new attribute #[Route] to document HTTP endpoints associated with classes and methods.

• Framework-agnostic: purely informational, does not enforce routing.
• Improves:
• Discoverability of endpoints in large codebases
• IDE navigation and code hints
• Static analysis and automated API documentation generation

Example:

#[Route('POST', '/resource/create')]
class ResourceCreateAction
{
    public function handle(): void
    {
        // logic
    }
}

#[Route(['PUT', 'PATCH'], '/resource/{id}/update')]
class ResourceUpdateAction
{
    public function handle(): void
    {
        // logic
    }
}

References:

• Previous PSR-19 proposal: PSR-19 @route PR