Refactor job model and optimize job streaming.

Updated the `JobModel` with foreign key relationships and string-based status to enhance database consistency, and improved job event streaming by using `jsonable_encoder` for better serialization. Also, streamlined dependencies by adding `urllib3` to handle HTTP requests.

backend/pyproject.toml

@@ -29,7 +29,8 @@ dependencies = [
     "python-dateutil~=2.8.2",
     "tomli>=2.0.1",
     "python-dotenv",
-    "psycopg2-binary"
+    "psycopg2-binary",
+    "urllib3~=2.2.1"
 ]
 [tool.pytest.ini_options]
 norecursedirs = ["backend/python-client"]