Update CI workflow to use new Cargo Chef based approach using pre-built Rust backend images for test stage

.forgejo/workflows/ci.yml

@@ -14,6 +14,7 @@ jobs:
       RUN_ID: ${{ github.run_id }}
       POSTGRES_IMG_DIGEST: ${{ secrets.POSTGRES_IMG_DIGEST }}
       RUST_IMG_DIGEST: ${{ secrets.RUST_IMG_DIGEST }}
+      PREBUILT_BACKEND_TEST_IMAGE: ${{ secrets.REGISTRY_HOST }}/${{ github.repository }}/sharenet-test-rust
 
     steps:
       - name: Checkout code
@@ -35,9 +36,41 @@ jobs:
           podman --remote version
           podman --remote run --rm alpine:3.20 echo "Hello from host rootless Podman!"
 
+      - name: Login to container registry with PAT
+        run: |
+          echo "${{ secrets.REGISTRY_TOKEN }}" | podman --remote login \
+            -u "${{ secrets.REGISTRY_USERNAME }}" \
+            --password-stdin \
+            "${{ secrets.REGISTRY_HOST }}"
+
       - name: Create network
         run: podman --remote network create integ-${{ env.RUN_ID }}
 
+      - name: Check if dependencies changed
+        id: check-deps
+        run: |
+          # Get hash of Cargo.toml and Cargo.lock
+          DEPS_HASH=$(sha256sum Cargo.toml Cargo.lock | sha256sum | cut -d' ' -f1)
+          echo "deps_hash=$DEPS_HASH" >> $GITHUB_OUTPUT
+          
+          # Check if image exists with this hash tag
+          if podman --remote manifest inspect "$PREBUILT_BACKEND_TEST_IMAGE:$DEPS_HASH" >/dev/null 2>&1; then
+            echo "rebuild_needed=false" >> $GITHUB_OUTPUT
+          else
+            echo "rebuild_needed=true" >> $GITHUB_OUTPUT
+          fi
+
+      - name: Build optimized Rust test image (if needed)
+        if: steps.check-deps.outputs.rebuild_needed == 'true'
+        run: |
+          podman --remote build \
+            -f backend/Dockerfile.test-rust \
+            -t "$PREBUILT_BACKEND_TEST_IMAGE:${{ steps.check-deps.outputs.deps_hash }}" \
+            -t "$PREBUILT_BACKEND_TEST_IMAGE:latest"
+          
+          podman --remote push "$PREBUILT_BACKEND_TEST_IMAGE:${{ steps.check-deps.outputs.deps_hash }}"
+          podman --remote push "$PREBUILT_BACKEND_TEST_IMAGE:latest"
+
       - name: Start PostgreSQL
         run: |  
           podman --remote run -d \
@@ -63,7 +96,7 @@ jobs:
             -v /home/ci-service/.cache:/c \
             alpine:3.20 sh -lc 'mkdir -p /c/cargo'
 
-      - name: Run backend tests (tar-pipe, no bind mount of source)
+      - name: Run backend tests with cached dependencies
         run: |
           set -euo pipefail
           set -o pipefail
@@ -73,11 +106,12 @@ jobs:
             -e CARGO_HOME=/cargo \
             -e DATABASE_URL=postgres://postgres:password@test-postgres-${{ env.RUN_ID }}:5432/sharenet_test \
             -v /home/ci-service/.cache/cargo:/cargo \
-            "$RUST_IMG_DIGEST" \
+            "$PREBUILT_BACKEND_TEST_IMAGE:${{ steps.check-deps.outputs.deps_hash }}" \
             sh -euxc '
               mkdir -p /workspace
               tar -x -C /workspace
               cd /workspace/backend
+              cargo chef cook --release --recipe-path /app/recipe.json
               cargo test --lib -- --test-threads=1
             '