refactor(features): rename SetupFont to AdjustTypography + reorganize

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.

src/features/AdjustTypography/ui/index.ts

@@ -0,0 +1 @@
+export { default as TypographyMenu } from './TypographyMenu/TypographyMenu.svelte';