Convert the eager typographySettingsStore singleton to getTypographySettingsStore()
(+ __resetTypographySettingsStore for tests) and update barrels and consumers
(TypographyMenu, FontSampler, SampleList, ComparisonView Line/SliderArea,
comparisonStore + its mock).
Fix a latent leak while here: the store ran $effect.root and discarded the
returned cleanup, so its storage-sync effects outlived every instance. Capture
the disposer and expose destroy(), which __reset now calls.
Structural:
- Merge factory + singleton from lib/settingsManager and model/state into
one model/store/typographySettingsStore/ slice
- Drop now-empty lib/ and model/state/ directories
Semantic:
- Rename feature SetupFont -> AdjustTypography (the feature owns
continuous typography adjustment, not one-time font setup)
- Drop "Manager" from TypographySettingsManager -> TypographySettingsStore
(class + factory); singleton typographySettingsStore unchanged
All consumers (Character, Line, SampleList, SliderArea, FontSampler,
comparisonStore) updated. Public barrel signature changed: now exports
createTypographySettingsStore and type TypographySettingsStore.