Add BLAZE_ENABLED and BLAZE_DEBUG env config

[ganyicz]

The scenario

Toggling Blaze on/off or enabling debug mode during development.

The problem

The only way to disable Blaze or enable debug mode is by calling Blaze::disable() or Blaze::debug() in a service provider. This means the change ends up in your committed code, which we don't want — it's easy to accidentally ship a Blaze::disable() call to production.

The solution

Add a config/blaze.php config file with BLAZE_ENABLED and BLAZE_DEBUG env vars:

return [
    'enabled' => env('BLAZE_ENABLED', true),
    'debug' => env('BLAZE_DEBUG', false),
];

BlazeManager reads these values on construction, and the config is publishable via php artisan vendor:publish --tag=blaze:config.