fix: PHPStan and test strictness improvements

Add bin/ scripts to PHPStan scanFiles, suppress property.onlyWritten for
by-ref test properties, add exhaustive default match arm, use explicit
expects() on mock stubs, fix data provider return type, and simplify
redundant null check in NotificationServiceTest.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/Service/Settings/SettingsDefaultsGatewayTest.php

@@ -28,6 +28,7 @@ class SettingsDefaultsGatewayTest extends TestCase
             'setDefaultTenantId' => $tenantRepository->expects($this->once())->method('find')->with($id)->willReturn(null),
             'setDefaultRoleId' => $roleRepository->expects($this->once())->method('find')->with($id)->willReturn(null),
             'setDefaultDepartmentId' => $departmentRepository->expects($this->once())->method('find')->with($id)->willReturn(null),
+            default => throw new \LogicException("Unknown setter: {$setter}"),
         };
 
         $this->assertFalse($gateway->$setter($id));