switch from dockerhub to ghcr, improve docker caching (#2695)

## Description:

Switch to GHCR for faster pulls/pushes and increased rate limits
Use cache-builder driver for better caching, so npm ci is cached if
dependencies don't change.



## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

## Please put your Discord username so you can be contacted if a bug or
regression is found:

evan

update.sh

@@ -28,8 +28,8 @@ echo "======================================================"
 # Container and image configuration
 CONTAINER_NAME="openfront-${ENV}-${SUBDOMAIN}"
 
-echo "Pulling ${DOCKER_IMAGE} from Docker Hub..."
-docker pull "${DOCKER_IMAGE}"
+echo "Pulling ${GHCR_IMAGE} from GitHub Container Registry..."
+docker pull "${GHCR_IMAGE}"
 
 echo "Checking for existing container..."
 # Check for running container
@@ -67,7 +67,7 @@ docker run -d \
     --env-file "$ENV_FILE" \
     --name "${CONTAINER_NAME}" \
     -v "cloudflared-${CONTAINER_NAME}:/etc/cloudflared" \
-    "${DOCKER_IMAGE}"
+    "${GHCR_IMAGE}"
 
 if [ $? -eq 0 ]; then
     echo "Update complete! New ${CONTAINER_NAME} container is running."