Optimize PR CI with custom Docker image and pre-installed dependencies

- Added `.ci/container/Dockerfile` to pre-install JDKs (8, 17, 21) and cache `cn1-binaries`.
- Added `.github/workflows/build-container.yml` to build and push the image to GHCR, ensuring the repository name is lowercased for valid Docker tags.
- Updated `.github/workflows/pr.yml` to run inside the new container, replacing `setup-java` with fast environment switching and linking pre-downloaded binaries.
- Fixed an issue where mixed-case repository names caused Docker build failures by enforcing lowercase tags in `build-container.yml` and using the canonical image name in `pr.yml`.

Author: google-labs-jules[bot]

.github/workflows/build-container.yml

@@ -24,9 +24,15 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
+      - name: Lowercase Repository Name
+        id: string
+        uses: ASzc/change-string-case-action@v5
+        with:
+          string: ${{ github.repository }}
+
       - name: Build and push Docker image
         uses: docker/build-push-action@v4
         with:
           context: .ci/container
           push: true
-          tags: ghcr.io/${{ github.repository }}/pr-ci-container:latest
+          tags: ghcr.io/${{ steps.string.outputs.lowercase }}/pr-ci-container:latest

.github/workflows/pr.yml

@@ -39,7 +39,7 @@ jobs:
 
     runs-on: ubuntu-latest
     container:
-      image: ghcr.io/${{ github.repository }}/pr-ci-container:latest
+      image: ghcr.io/codenameone/codenameone/pr-ci-container:latest
       options: --privileged
     strategy:
       fail-fast: false