fix(docs): resolve documentation drift and add missing content

- Fix fictional SettingGateway/SettingService references with actual
  multi-gateway pattern (AdminSettingsService + domain-specific gateways)
- Replace non-existent gridQueryLimitOffset()/gridQueryOrderDir() with
  actual gridParseFiltersFromSchemaFile()
- Normalize bin/doctor.php references to canonical bin/console doctor
- Add i18n_path contract to module manifest docs
- Document module:validate and make:module CLI commands
- Add APP_VENDOR_PHP_ISSUES_MODE env var to config reference
- Remove invalid label field from notifications module permissions
  (violates manifest schema additionalProperties: false)

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

modules/notifications/module.php

@@ -70,7 +70,6 @@ return [
     'permissions' => [
         [
             'key' => 'notifications.view',
-            'label' => 'Notifications: View',
             'description' => 'View and manage own notifications',
         ],
     ],