Introduce db() Helper to Encapsulate Database DI Lookup

Description

Across the Database and Model layer (specifically within TransactionTrait, RelationalTrait, MigrationManager, and ModelFactory), the Database::class is manually requested from the Dependency Injection container using this repetitive boilerplate:

if (!Di::isRegistered(Database::class)) {
    Di::register(Database::class);
}

$db = Di::get(Database::class); // usually chained with ->getOrmClass() or similar.

While the overall framework implements utility helpers (like config(), session(), view()) to cleanly proxy these exact DI resolutions, the Database module is entirely missing a db() helper!

As a result, domain traits and managers are bloated with raw container logic, violating the service locator pattern established by the rest of the application.

Proposed Solution

1. Create the Helper: Introduce a file at src/Database/Helpers/db.php that exposes a db() function.

<?php

use Quantum\Database\Database;
use Quantum\Di\Di;

/**
 * Gets the Database service instance
 * @throws \Quantum\Di\Exceptions\DiException|\ReflectionException
 */
function db(): Database
{
    if (!Di::isRegistered(Database::class)) {
        Di::register(Database::class);
    }

    return Di::get(Database::class);
}

2. Refactor Codebase: Go through TransactionTrait, RelationalTrait, MigrationManager, and ModelFactory and replace the verbose DI blocks with the clean helper call. For example, in TransactionTrait::resolveTransaction():

-        if (!Di::isRegistered(Database::class)) {
-            Di::register(Database::class);
-        }
-
-        $db = Di::get(Database::class)->getOrmClass();
+        $db = db()->getOrmClass();

3. Update Autoloading: Ensure src/Database/Helpers/db.php is properly configured to be autoloaded (either via composer or the LoadHelpersStage).

4. Unit Tests:

   • Create a corresponding tests/Unit/Database/Helpers/DbHelperTest.php file to explicitly test the new locator method.
   • Run the full test suite over the Database and Model modules to verify that RelationalTrait, TransactionTrait, MigrationManager and ModelFactory continue to operate identically under the rewritten backend logic.