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/widgets/ComparisonView/ui/Line/Line.svelte

@@ -11,7 +11,7 @@ import {
     type ComparisonLine,
     computeLineRenderModel,
 } from '$entities/Font';
-import { typographySettingsStore } from '$features/AdjustTypography';
+import { getTypographySettingsStore } from '$features/AdjustTypography';
 import { getComparisonStore } from '../../model';
 import Character from '../Character/Character.svelte';
 
@@ -36,7 +36,7 @@ const comparisonStore = getComparisonStore();
 
 const model = $derived(computeLineRenderModel(line, split, windowSize));
 
-const typography = $derived(typographySettingsStore);
+const typography = getTypographySettingsStore();
 const fontA = $derived(comparisonStore.fontA);
 const fontB = $derived(comparisonStore.fontB);