Docker Compose depends on Redis but backend does not use it

[RonaldRonnie]

Description:

docker-compose.yml starts Redis and the backend depends_on: redis, but:

• pom.xml has no Redis dependency (e.g. spring-boot-starter-data-redis)
• There is no application-docker.yml or Redis configuration in the backend

So the backend never connects to Redis. Docs and architecture describe Redis for caching/sessions; the code does not implement it.

Acceptance criteria:

• Either: add Redis dependency and implement Redis usage (e.g. session/cache) and document it, or
• Remove Redis service and dependency from docker-compose.yml and update docs until Redis is implemented