Added RDEPUBTextPageGeometry value types and threaded page geometry through RDEPUBTextLayoutFrame, RDEPUBTextPage, and both text book builders.
Geometry now comes from CoreText line offsets instead of inferred page offsets, while pageStartOffset, pageEndOffset, fragmentOffsets, and RDEPUBTextOffsetRangeInfo semantics remain unchanged.
Added reusable page query helpers for range-to-rect and rect or point back to absolute text ranges.
Verification
build_sim for ReadViewDemo on iOS Simulator succeeded on 2026-05-22.