Documents the stopPropagation guarantee: clicking the trash button must
not trigger the annotation's onclick (which opens the block detail panel)
while the delete confirm is in progress.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Adds a trash icon button (44×44 px touch target) directly on each annotation shape in transcription mode so users can delete a block without navigating through the sidebar. Includes keyboard support (Delete key), confirm dialog via ConfirmService, prop-chain wiring through DocumentViewer → PdfViewer → AnnotationLayer → AnnotationShape, and orphaned-annotation fallback (calls DELETE /annotations/{id} when no block is linked). Backend security regression test added for deleteBlock 403 on READ_ALL.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
