Fix RefHover popup region on mupdf per-glyph ink boxes

[koppor]

Problem

The citation/reference hover popup (RefHover) cropped to the wrong region on many real PDFs: a clipped narrow strip, or a full-page landscape fallback showing several entries, instead of the single target bibliography entry.

Root cause: the region detectors in RefHoverDetect.cpp key off coords[i].y as a line coordinate, assuming glyphs on one line share a top. EngineBase::GetTextForPage returns mupdf's tight per-glyph ink boxes, whose tops vary within a line (a period/comma sits well below a capital; ascenders and brackets higher). So the trailing . of the previous bibliography entry could fall into the destination band and hijack the entry-start glyph.

(This only reproduces against the real engine — PyMuPDF/fitz rawdict reports near-uniform tops and hides it.)

Fix

• NormalizeGlyphLines: cluster glyphs by baseline (y + dy, which is stable across a line) and flatten each line to a uniform top-aligned row before detection. RefHoverOnTimer normalizes the page coords once and passes them to both DetectEquationBox and DetectEntryBox.
• DetectEntryBox bracket path — derive columnRightX from the body run, bridging the hanging-indent labelsep gap (capped so it can't jump a column gutter). A narrow biblatex label ([TA05]) no longer collapses the box width and clips the entry.
• DetectEntryBox bracket path — trailing-gap trim so a last-on-page entry (no sibling [ below it) ends at its last line instead of swallowing the page-number footer.

Testing

• RefHover_ut: added coverage for baseline normalization, the variable-top entry-start hijack, narrow-label full width, 2-column safety, and the footer trim. test_util passes all unit tests.
• Verified against the real engine on two biblatex PDFs (single- and multi-page bibliographies): every citation link now yields a correct full-width single-entry popup region.

🤖 Generated with Claude Code

[kjk]

thanks!