Fix migration using wrong config key for database connection (#3)

## Summary
- The migration stub was referencing `barstool.database_connection` but
the actual config key is `barstool.connection`
- Uses null coalescing to fall back to the old key for backwards
compatibility with anyone who may have published the migration with the
old key
- Adds test coverage for the migration connection config
## Test plan
- [x] New test verifies `barstool.connection` is used
- [x] New test verifies fallback to `barstool.database_connection`
- [x] New test verifies `barstool.connection` takes priority when both
are set
  - [x] Full test suite passes (18 tests, 129 assertions)
  - [x] PHPStan passes

Author: craigpotter

database/migrations/create_barstools_table.php.stub

@@ -12,7 +12,7 @@ return new class extends Migration
      */
     public function getConnection(): string|null
     {
-        return config('barstool.database_connection');
+        return config('barstool.connection') ?? config('barstool.database_connection');
     }
 
     /**

tests/BarstoolTest.php

@@ -91,6 +91,24 @@
     expect(Barstool::make()->getConnectionName())->toBe('sqlite');
 });
 
+it('uses the correct config key for the migration database connection', function () {
+    $migration = include __DIR__.'/../database/migrations/create_barstools_table.php.stub';
+
+    // The migration should use the 'barstool.connection' config key
+    config()->set('barstool.connection', 'pgsql');
+    expect($migration->getConnection())->toBe('pgsql');
+
+    // It should fall back to 'barstool.database_connection' for backwards compatibility
+    config()->set('barstool.connection', null);
+    config()->set('barstool.database_connection', 'sqlite');
+    expect($migration->getConnection())->toBe('sqlite');
+
+    // 'barstool.connection' takes priority over 'barstool.database_connection'
+    config()->set('barstool.connection', 'mysql');
+    config()->set('barstool.database_connection', 'sqlite');
+    expect($migration->getConnection())->toBe('mysql');
+});
+
 it('can change the number of days to keep recordings for', function () {
     // Check the default value is 30
     expect(config('barstool.keep_for_days'))->toBe(30);