Migrate CI to use common-ci-configuration templates

Summary

• Migrate detect_changes, tavern tests, and sync job to use templates from common-ci-configuration
• Significant code reduction while maintaining all functionality

Changes

• detect_changes: Now extends .haf_app_detect_changes template
• pattern-test: Uses tavern templates (.tavern_test_variables, .tavern_install_deps)
• sync: Refactored from ~150 lines to ~50 lines using:
  • .haf_app_sync_variables
  • .haf_app_sync_setup
  • .haf_app_fetch_haf_cache
  • .haf_app_copy_blockchain
  • .haf_app_copy_datadir
  • .haf_app_sync_shutdown
  • .haf_app_sync_save_cache
  • .haf_app_sync_cleanup
  • .haf_app_sync_artifacts

Dependencies

• Requires common-ci-configuration!120 (merged) to be merged first

Test plan

• Full pipeline passing on feature branch