refacto init_script container and add pose image at init

[fe51]

Refactor init_script container & add pose image upload at init

This PR introduce the following modifications :

• Refactored init_script.py: extracted utility functions (get_token, api_request, read_json_file, write_json_file, download_images_if_needed) into a new utils.py module for better readability and reusability.
• Added pose image upload at initialization: during the camera setup phase, the script now downloads sample images from a GitHub release (already used elsewhere in this repo) and uploads a pose image to each camera (with configurable per-org exclusions).
• Dockerfile & requirements updated: added Pillow and pyroclient dependencies to support image handling.
• Minor notebook fixes: small adjustments in camera_status, continuous_alert, and send_real_alerts notebooks.

[MateoLostanlen]

LGTM, tested it works ! Thanks