fix: uploaded material persistence and docker-compose

[ethanlacerenza]

What

Fix uploaded material persistence and remove deprecated version field from docker-compose.yml.

Why

• Uploaded files were stored inside the container and lost on every restart
• The version key in docker-compose.yml is deprecated in Compose v2 and generates a warning on every command

Changes

• Added a named Docker volume mapped to the uploads directory so data persists across container restarts
• Removed the top-level version field from docker-compose.yml