Security hardening: run services as non-root user

[Dev10-sys]

This change updates the containers to run as a non-root user instead of root.

Summary of changes:

• Created a dedicated user named tuf (UID 1000) inside the containers
• Updated file and directory permissions so the tuf user can access required paths
• Changed internal service ports from 80 to 8080 so root privileges are not required
• Updated container and deployment configuration to enforce non-root execution
• Adjusted supervisor configuration for worker to use writable directories
• Updated Helm charts to set securityContext with runAsNonRoot

Why this change:
Running containers as root is not recommended for security reasons. Running as a non-root user follows container security best practices and reduces risk in production environments.

Testing:
The configuration was verified to ensure the API and Worker can start under non-root permissions and the container setup remains consistent with docker-compose and Helm deployment.

This change is coordinated with the umbrella repository PR:
repository-service-tuf/repository-service-tuf#934