hooks/fancy: handle_output: remember last line and overwrite it if both are "BUSY" with the same text.

This is to implement status updates.
scripts/globals, hooks/fancy: add report_update() for incremental status updates.
hooks/fancy: report_update: output status updates at the same indentation level as the initial report.
hooks/fancy: print_prefix_raw and callers: colorize only main text, not reason appendix.

This fixes matching for status update lines in handle_output.