Replaces the hardcoded maxMarkerPreviewDuration = 20 constant in
pkg/scene/generate/marker_preview.go with a configurable setting on
ConfigGeneral, mirroring the PreviewSegments wiring pattern.
- Default 20 preserves existing behavior for all installs
- Positive N sets the ceiling in seconds
- 0 (or any value <= 0) disables the ceiling, honoring explicit
endSeconds verbatim
- Adds logger.Warnf for non-positive intervals to aid diagnosis of
imported or malformed marker data
- Incidentally prevents zero/negative-duration ffmpeg calls that
were possible under the previous logic
Context: closed issue #6852 (template non-conformance), Discussion
#6851 (mobile-first direction).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
e9e427772b