Refactor restart tracking and add missing model casts

- Consolidate duplicate restart tracking logic in GetContainersStatus
- Add last_restart_type string cast to all 8 standalone database models

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/Models/StandaloneMysql.php

@@ -21,6 +21,7 @@ class StandaloneMysql extends BaseModel
         'mysql_root_password' => 'encrypted',
         'restart_count' => 'integer',
         'last_restart_at' => 'datetime',
+        'last_restart_type' => 'string',
     ];
 
     protected static function booted()