Add job processing system with streaming endpoint

Introduced a `processing` router to handle job streaming using server-sent events. Added `Jobs` and `JobStatus` models for managing job-related data, along with database creation logic. Updated the `sample` router to create new job entries during experiment creation.

.gitlab-ci.yml

@@ -73,7 +73,7 @@ release:
 
   script:
     # build and run commands within docker container context
-    - docker compose --env-file frontend/.env.dev build backend
+    - docker compose --env-file frontend/.env.test build backend
 
     # Run commands inside your 'backend' service container
     - docker compose run --rm backend mkdir -p /app/backend/ssl