refactor(typography): lazy getTypographySettingsStore + fix effect leak

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.

src/features/AdjustTypography/index.ts

@@ -1,9 +1,9 @@
 export {
     createTypographySettingsStore,
+    getTypographySettingsStore,
     MULTIPLIER_L,
     MULTIPLIER_M,
     MULTIPLIER_S,
     type TypographySettingsStore,
-    typographySettingsStore,
 } from './model';
 export { TypographyMenu } from './ui';