Taught RDEPUBTextLayouter to consume semantic hints and emit semanticBoundary breaks when explicit page-break or avoid-break rules should influence pagination.
Expanded page metadata and layout frames to retain block kinds, semantic hints, and attachment placements alongside the existing attachment and break diagnostics.
Propagated the richer pagination diagnostics through RDEPUBTextBookBuilder and RDPlainTextBookBuilder, so chapter summaries can now explain attachment-heavy and block-sensitive pagination behavior.
Verification
build_sim for ReadViewDemo on iOS Simulator succeeded on 2026-05-22.
