feat(bounding-box): support bounding box highlights in ImageAnnotator

[dlasecki-box]

Adds bounding box highlight rendering and scroll-to-highlight support for image files.

Changes:

• Add BoundingBoxHighlightManager to ImageAnnotator when viewMode is boundingBoxes, with proper manager lifecycle on view mode switches
• Standardize scrollToBoundingBoxHighlight by moving shared logic from DocumentAnnotator into BaseAnnotator, with subclass hooks (getScrollReferenceForHighlight, getAdjustedScrollOffsets) for file-type–specific behavior
• ImageAnnotator implements scroll hooks with rotation-aware offset adjustment
• Skip DeselectManager in bounding box mode (no annotation creation needed)
• Add unit tests for new image annotator behavior

It's a followup to that PR where Bounding Boxes support was added for documents