✨ feat: make EuroOffice the default editor for new and existing installs

- isEuroofficeEnabled default: false → true
- isCollaboraEnabled default: true → false
- Add eurooffice to STARTUP_APPS so it installs automatically
- performMigrations(): one-time migration (guarded by
  eurooffice_default_migration_v1 flag) that forces existing installs
  to switch to EuroOffice on next mastercontainer start, overriding
  any prior explicit editor choice
- Call performMigrations() at index.php bootstrap

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: James Manuel <moodyjmz@users.noreply.github.com>

php/public/index.php

@@ -25,6 +25,7 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 require __DIR__ . '/../vendor/autoload.php';
 
 $container = \AIO\DependencyInjection::GetContainer();
+$container->get(\AIO\Data\ConfigurationManager::class)->performMigrations();
 $dataConst = $container->get(\AIO\Data\DataConst::class);
 
 // Create app