Mock data lived in lib/ and was re-exported through the slice's
production index.ts, advertising fixtures as part of the public API.
Move it to a testing/ segment and drop it from index.ts; consumers now
import explicitly via the $entities/Font/testing subpath.
Repoints the four mock consumers (FontApplicator story, sizeResolver
and fontCatalogStore specs, comparisonStore test) to the new subpath.
createFontRowSizeResolver was reaching into TextLayoutEngine, which
internally called pretext's heavy layoutWithLines and then walked
per-grapheme cursors to build chars arrays. The resolver discarded all
that work and used only totalHeight.
Replace with direct prepare + layout from @chenglou/pretext — pretext
docs explicitly recommend layout() (not layoutWithLines) for the resize
hot path: pure arithmetic on cached segment widths, no canvas calls, no
string allocations.
Test spies on TextLayoutEngine.prototype.layout migrated to vi.mock-ed
pretext layout (pretext's ESM exports are frozen — vi.spyOn fails with
"Cannot redefine property").
TextLayoutEngine marked @deprecated since it has no remaining
consumers; slated for removal after a release cycle.