Add hived data preparation template for submodule-free HAF apps

This enables HAF applications to use pre-built hived images from the
registry instead of building from submodules, eliminating the deep
haf → hive submodule dependency chain.

Changes:
- Add .prepare_hived_data_5m template that fetches all scripts at
  runtime and uses pre-built hived images
- Add hived_config_5M.ini for standalone hived 5M block replay
- Document pre-built image usage in haf-app-tools README
- Update header docs with pre-built image examples