Add sync job component templates for HAF apps

Composable building blocks for sync jobs:
- .haf_app_sync_variables - common directory and compose variables
- .haf_app_sync_setup - docker login and git safe.directory
- .haf_app_fetch_haf_cache - fetch HAF replay data from local/NFS
- .haf_app_copy_datadir - copy datadir and fix ownership
- .haf_app_copy_blockchain - copy block_log to docker directory
- .haf_app_sync_shutdown - checkpoint, collect logs, compose down
- .haf_app_sync_save_cache - save to local and push to NFS
- .haf_app_sync_cleanup - after_script cleanup
- .haf_app_sync_artifacts - standard artifacts pattern

Apps can compose their sync job using !reference tags to include
only the pieces they need, while keeping app-specific logic inline.