Layout: exclude floating anchors from line font metrics (task 256) (#2462)

Co-authored-by: Brandon Thomas <echelon@gmail.com>

docs/gaps.md

@@ -117,6 +117,7 @@ The Language dialog reads effective character formatting, including document def
 | 2026-10-14 | trivial | #19 narrowed: ODT export done (master page and page layout per section, columned `text:section`s) |
 | 2026-10-15 | trivial | Additive paragraph spacing retains the full before-space after a section page break; ordinary overlapping spacing is unchanged. |
 | 2026-10-15 | trivial | Exact line spacing keeps the run font baseline around tall equations; automatic and minimum spacing still grow for math. |
+| 2026-10-16 | trivial | Zero-extent drawing anchors contribute no inline font height. Synthetic regressions. |
 | 2026-10-14 | trivial | Row table border exceptions fixed; other row table exceptions remain unsupported |
 | 2026-10-12 | minor | Czech proofing review: short-word splits rank after deletion, NOSUGGEST excludes suggestions while accepting typed forms, affix comments apply only to headers, ratios keep spaces and repeated-word messages use Czech quotes; synthetic engine end-to-end and latency checks |
 | 2026-10-12 | minor | Czech spelling from the installed Hunspell dictionary, runtime-table suggestions and generic checks; Czech interface writes cs-CZ documents; no Czech hyphenation patterns bundled; estimates unchanged |