feat(ci): auto-update docker compose examples when a full starter is published

Description

When a new full starter is generated via the Publish Starter GitHub Action workflow, the docker/docker-compose-examples/ files that hard-code the starter artifact URL need to be updated to point to the newly published starter.

Currently the workflow already does this for the empty starter:

1. Updates parent/pom.xml with the new starter.deploy.version
2. Opens an automated PR via peter-evans/create-pull-request@v6
3. Appends a :exclamation: Approvals required PR link to the Slack #log-starter notification

The same pattern should be replicated for the full starter, targeting the CUSTOM_STARTER_URL value inside the docker compose examples instead of pom.xml.

Affected file (current reference):

docker/docker-compose-examples/single-node/docker-compose.yml
CUSTOM_STARTER_URL: 'https://repo.dotcms.com/artifactory/libs-release-local/com/dotcms/starter/20260409/starter-20260409.zip'

Acceptance Criteria

• When the Publish Starter workflow runs with type: full and dry-run: false, a step updates CUSTOM_STARTER_URL in all docker compose example files that reference a full starter artifact URL
• An automated PR is created (via peter-evans/create-pull-request@v6) containing only the docker compose file changes, using an appropriate branch name (e.g., <issue-number>-update-docker-compose-starter-<version>-<run_id>)
• The PR title and body clearly identify the new starter version and that the PR was created automatically
• The PR is labeled with full-starter and automated pr
• The Slack #log-starter notification for a full starter includes the PR link with the same :exclamation: Approvals required alert format already used for the empty starter
• The new steps are guarded by type == 'full' && dry-run == 'false' conditions (mirroring the empty starter guards)
• Dry-run mode skips PR creation and omits the PR link from any Slack message

Additional Context

• Reference implementation (empty starter path): .github/workflows/cicd_manual_publish-starter.yml — steps update-pom, create-pull-request, and the PR_ALERT block inside Compose Message
• The issue-number workflow input (already required) should be reused for the full-starter branch name, consistent with the empty starter approach

Start with .github/workflows/cicd_manual_publish-starter.yml and inspect the existing update-pom, create-pull-request, and PR_ALERT steps for the empty-starter path. Add the corresponding full-starter workflow behavior for CUSTOM_STARTER_URL, then verify that full non-dry runs create the labeled PR and Slack alert while dry runs skip both.