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/ui/TypographyMenu/TypographyMenu.svelte

@@ -23,7 +23,7 @@ import {
     MULTIPLIER_L,
     MULTIPLIER_M,
     MULTIPLIER_S,
-    typographySettingsStore,
+    getTypographySettingsStore,
 } from '../../model';
 
 interface Props {
@@ -46,6 +46,7 @@ interface Props {
 let { class: className, hidden = false, open = $bindable(false) }: Props = $props();
 
 const responsive = getContext<ResponsiveManager>('responsive');
+const typographySettingsStore = getTypographySettingsStore();
 
 /**
  * Sets the common font size multiplier based on the current responsive state.