Refactor Jenkinsfile to utilize Docker for Python environment setup during backend testing, enhancing consistency and isolation of dependencies.

Jenkinsfile

@@ -37,7 +37,6 @@ pipeline {
           set -euxo pipefail
           echo "== Test backend stage started =="
           echo "Workspace: $WORKSPACE"
-          python3 --version
           docker --version
 
           DB_CONTAINER="anexo76-test-db-${BUILD_NUMBER}"
@@ -46,8 +45,10 @@ pipeline {
           DB_PASS="anexo76"
           DB_PORT="55432"
           export TEST_DATABASE_URL="postgresql://${DB_USER}:${DB_PASS}@127.0.0.1:${DB_PORT}/${DB_NAME}"
+          PY_CONTAINER="anexo76-test-py-${BUILD_NUMBER}"
 
           cleanup() {
+            docker rm -f "$PY_CONTAINER" >/dev/null 2>&1 || true
             docker rm -f "$DB_CONTAINER" >/dev/null 2>&1 || true
           }
           trap cleanup EXIT
@@ -69,16 +70,21 @@ pipeline {
           done
           docker exec "$DB_CONTAINER" pg_isready -U "$DB_USER" -d "$DB_NAME"
 
-          VENV="$WORKSPACE/.pytest-venv"
-          python3 -m venv "$VENV"
-          . "$VENV/bin/activate"
-
-          python -m pip install --upgrade pip
-          pip install -r "$WORKSPACE/backend/requirements.txt"
-
-          cd "$WORKSPACE/backend"
-          alembic upgrade head
-          pytest -q tests -v -ra -s
+          docker run --name "$PY_CONTAINER" --rm \
+            --network host \
+            -e TEST_DATABASE_URL="$TEST_DATABASE_URL" \
+            -v "$WORKSPACE:/workspace" \
+            -w /workspace \
+            python:3.12-slim \
+            sh -lc '
+              set -euxo pipefail
+              python --version
+              python -m pip install --upgrade pip
+              pip install -r /workspace/backend/requirements.txt
+              cd /workspace/backend
+              alembic upgrade head
+              pytest -q tests -v -ra -s
+            '
         '''
       }
     }