Chunked dispatch of campaign email jobs and id-based job payloads

[ProgrammerHasan]

Motivation

• Avoid loading all campaign recipients into memory when sending a campaign to improve scalability and memory usage.
• Reduce job payload size and avoid serializing whole Eloquent models into queued jobs to prevent stale/large data being serialized.
• Make job execution more robust by loading current recipient relations at run-time and safely handling missing recipients.

Description

• Changed SendCampaignEmailJob to accept an int $recipientId instead of a CampaignRecipient model and to load the CampaignRecipient with campaign and contact relations inside handle, returning early if the recipient no longer exists.
• Updated CampaignService::send to iterate recipients using ->recipients()->select('id')->chunkById(100, ...) and dispatch SendCampaignEmailJob with recipientId: $recipient->id to avoid loading all recipients at once.
• Kept existing status updates and logging behavior in the job (Status::SENT / Status::FAILED) while preserving the Mail::to(...)->send(...) call and error handling.

Testing

• No automated tests were executed for this change.

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Codex Task