refactor: extract magic constants — wave 2 (TanStack Query defaults)

Promote the duplicated query lifecycle constants in \$shared/api/queryClient.ts:

- staleTime (5 minutes) -> DEFAULT_QUERY_STALE_TIME_MS
- gcTime (10 minutes)   -> DEFAULT_QUERY_GC_TIME_MS
- retry (3)             -> QUERY_RETRY_COUNT
- retryDelay (1s base, 30s cap) -> QUERY_RETRY_BASE_DELAY_MS + QUERY_RETRY_MAX_DELAY_MS

fontCatalogStore and availableFilterStore now import the stale/gc
constants instead of re-deriving '5 * 60 * 1000' / '10 * 60 * 1000'.

fontCatalogStore.svelte.spec.ts's queryClient mock now passes through
the new named exports via importOriginal so the consumer's imports
resolve.

src/entities/Font/model/store/fontCatalogStore/fontCatalogStore.svelte.spec.ts

@@ -19,11 +19,15 @@ import {
 import type { UnifiedFont } from '../../types';
 import { FontCatalogStore } from './fontCatalogStore.svelte';
 
-vi.mock('$shared/api/queryClient', () => ({
-    queryClient: new QueryClient({
-        defaultOptions: { queries: { retry: 0, gcTime: 0 } },
-    }),
-}));
+vi.mock('$shared/api/queryClient', async importOriginal => {
+    const actual = await importOriginal<typeof import('$shared/api/queryClient')>();
+    return {
+        ...actual,
+        queryClient: new QueryClient({
+            defaultOptions: { queries: { retry: 0, gcTime: 0 } },
+        }),
+    };
+});
 vi.mock('../../../api', () => ({ fetchProxyFonts: vi.fn() }));
 
 import { queryClient } from '$shared/api/queryClient';

src/entities/Font/model/store/fontCatalogStore/fontCatalogStore.svelte.ts

@@ -1,4 +1,8 @@
-import { queryClient } from '$shared/api/queryClient';
+import {
+    DEFAULT_QUERY_GC_TIME_MS,
+    DEFAULT_QUERY_STALE_TIME_MS,
+    queryClient,
+} from '$shared/api/queryClient';
 import {
     type InfiniteData,
     InfiniteQueryObserver,
@@ -427,8 +431,8 @@ export class FontCatalogStore {
                 const next = lastPage.offset + lastPage.limit;
                 return next < lastPage.total ? { offset: next } : undefined;
             },
-            staleTime: hasFilters ? 0 : 5 * 60 * 1000,
-            gcTime: 10 * 60 * 1000,
+            staleTime: hasFilters ? 0 : DEFAULT_QUERY_STALE_TIME_MS,
+            gcTime: DEFAULT_QUERY_GC_TIME_MS,
         };
     }