- Move output_format.h from userspace/falco/ to userspace/engine/ to
fix reverse dependency (engine layer was including from app layer);
update all include paths accordingly
- Add SPDX-License-Identifier to output_format.h
- Remove leftover m_first_event_in_category field from MarkdownFormatter
(was set in begin_category() but never read)
- Emit deprecation warning to stderr when --markdown is used
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Signed-off-by: Paolo Polidori <paolo.polidori@sysdig.com>