Add {image: path} directive to embed images at any position within a song's
sections. SongLine gains an optional imagePath field; when set, the line
represents an inline image rather than chord/lyric content. The renderer
scales and centers images within the content width. MeasurementEngine
reserves 40mm height per inline image for layout calculations.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>