[Recording Oracle] Webhook notification on chunk completion

[portuu3]

Description
The Recording Oracle should send a webhook to the Reputation Oracle after each chunk is processed to notify about chunk completion.

Motivation
The webhook notification enables real-time tracking of job progress and allows the system to trigger further actions (e.g., updating the final result file, making partial payments).

Implementation details

• Add a webhook notification system to send chunk_completed event after each chunk is appended to the file.