Add Docker layer caching to improve build performance

Implements GitHub Actions cache backend (type=gha) for Docker layer caching in both workflows:

**update-current-image.yml:**
- Added cache-from: type=gha to both 'Build' and 'Build and push Image' steps
- Added cache-to: type=gha,mode=max to store full cache for reuse

**dockerimage.yml:**
- Added cache-from: type=gha to 'Build Image' step
- Added cache-to: type=gha,mode=max for caching Docker layers

**Benefits:**
- Reuses Docker layers across builds
- Significantly faster builds when layers haven't changed
- No external infrastructure needed (uses GitHub Actions cache)
- Cache is scoped per workflow run context

Author: chorrell

.github/workflows/dockerimage.yml

@@ -72,6 +72,8 @@ jobs:
           platforms: linux/${{ matrix.platform }}
           load: true
           tags: ${{ env.IMAGE_NAME }}-${{ env.LATEST_VERSION }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
       - name: Test Image
         run: docker run --rm ${{ env.IMAGE_NAME }}-${{ env.LATEST_VERSION }} -e "console.log('Hello from Node.js ' + process.version)"

.github/workflows/update-current-image.yml

@@ -117,6 +117,8 @@ jobs:
           platforms: linux/${{ matrix.platform }}
           load: true
           tags: ${{ env.IMAGE_NAME }}-${{ needs.check_version.outputs.NODE_VERSION }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max
 
       - name: Test Image
         run: docker run --rm ${{ env.IMAGE_NAME }}-${{ needs.check_version.outputs.NODE_VERSION }} -e "console.log('Hello from Node.js ' + process.version)"
@@ -142,3 +144,5 @@ jobs:
           sbom: true
           tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
+          cache-from: type=gha
+          cache-to: type=gha,mode=max