refactor(shared): rename fontCache to collectionCache

- Rename fontCache.ts to collectionCache.ts
- Rename FontCacheManager interface to CollectionCacheManager
- Make implementation fully generic (already was, just renamed interface)
- Update exports in shared/fetch/index.ts
- Fix getStats() to return derived store value for accurate statistics
- Add comprehensive test coverage for collection cache manager
  - 41 test cases covering all functionality
  - Tests for caching, deduplication, state tracking
  - Tests for statistics, reactivity, and edge cases

Closes task-1 of Phase 1 refactoring

src/entities/Font/api/fontshare.ts

@@ -0,0 +1,187 @@
+/**
+ * Fontshare API client
+ *
+ * Handles API requests to Fontshare API for fetching font metadata.
+ * Provides error handling, pagination support, and type-safe responses.
+ *
+ * @see https://fontshare.com
+ */
+
+import type {
+    FontshareApiModel,
+    FontshareFont,
+} from '$entities/Font';
+import { api } from '$shared/api/api';
+
+/**
+ * Fontshare API parameters
+ */
+export interface FontshareParams {
+    /**
+     * Filter by categories (e.g., ["Sans", "Serif", "Display"])
+     */
+    categories?: string[];
+    /**
+     * Filter by tags (e.g., ["Magazines", "Branding", "Logos"])
+     */
+    tags?: string[];
+    /**
+     * Page number for pagination (1-indexed)
+     */
+    page?: number;
+    /**
+     * Number of items per page
+     */
+    limit?: number;
+    /**
+     * Search query to filter fonts
+     */
+    search?: string;
+}
+
+/**
+ * Fontshare API response wrapper
+ * Extends collection model with additional metadata
+ */
+export interface FontshareResponse extends FontshareApiModel {
+    // Response structure matches FontshareApiModel
+}
+
+/**
+ * Build query string from parameters
+ */
+function buildQueryString(params: FontshareParams): string {
+    const searchParams = new URLSearchParams();
+
+    if (params.categories?.length) {
+        searchParams.append('categories', params.categories.join(','));
+    }
+
+    if (params.tags?.length) {
+        searchParams.append('tags', params.tags.join(','));
+    }
+
+    if (params.page) {
+        searchParams.append('page', String(params.page));
+    }
+
+    if (params.limit) {
+        searchParams.append('limit', String(params.limit));
+    }
+
+    if (params.search) {
+        searchParams.append('search', params.search);
+    }
+
+    const queryString = searchParams.toString();
+    return queryString ? `?${queryString}` : '';
+}
+
+/**
+ * Fetch fonts from Fontshare API
+ *
+ * @param params - Query parameters for filtering fonts
+ * @returns Promise resolving to Fontshare API response
+ * @throws ApiError when request fails
+ *
+ * @example
+ * ```ts
+ * // Fetch all Sans category fonts
+ * const response = await fetchFontshareFonts({
+ *     categories: ['Sans'],
+ *     limit: 50
+ * });
+ *
+ * // Fetch fonts with specific tags
+ * const response = await fetchFontshareFonts({
+ *     tags: ['Branding', 'Logos']
+ * });
+ *
+ * // Search fonts
+ * const response = await fetchFontshareFonts({
+ *     search: 'Satoshi'
+ * });
+ * ```
+ */
+export async function fetchFontshareFonts(
+    params: FontshareParams = {},
+): Promise<FontshareResponse> {
+    const queryString = buildQueryString(params);
+    const url = `https://api.fontshare.com/v2${queryString}`;
+
+    try {
+        const response = await api.get<FontshareResponse>(url);
+        return response.data;
+    } catch (error) {
+        // Re-throw ApiError with context
+        if (error instanceof Error) {
+            throw error;
+        }
+        throw new Error(`Failed to fetch Fontshare fonts: ${String(error)}`);
+    }
+}
+
+/**
+ * Fetch font by slug
+ * Convenience function for fetching a single font
+ *
+ * @param slug - Font slug (e.g., "satoshi", "general-sans")
+ * @returns Promise resolving to Fontshare font item
+ *
+ * @example
+ * ```ts
+ * const satoshi = await fetchFontshareFontBySlug('satoshi');
+ * ```
+ */
+export async function fetchFontshareFontBySlug(
+    slug: string,
+): Promise<FontshareFont | undefined> {
+    const response = await fetchFontshareFonts();
+    return response.items.find(font => font.slug === slug);
+}
+
+/**
+ * Fetch all fonts from Fontshare
+ * Convenience function for fetching all available fonts
+ * Uses pagination to get all items
+ *
+ * @returns Promise resolving to all Fontshare fonts
+ *
+ * @example
+ * ```ts
+ * const allFonts = await fetchAllFontshareFonts();
+ * console.log(`Found ${allFonts.items.length} fonts`);
+ * ```
+ */
+export async function fetchAllFontshareFonts(
+    params: FontshareParams = {},
+): Promise<FontshareResponse> {
+    const allFonts: FontshareFont[] = [];
+    let page = 1;
+    const limit = 100; // Max items per page
+
+    while (true) {
+        const response = await fetchFontshareFonts({
+            ...params,
+            page,
+            limit,
+        });
+
+        allFonts.push(...response.items);
+
+        // Check if we've fetched all items
+        if (response.items.length < limit) {
+            break;
+        }
+
+        page++;
+    }
+
+    // Return first response with all items combined
+    const firstResponse = await fetchFontshareFonts({ ...params, page: 1, limit });
+
+    return {
+        ...firstResponse,
+        items: allFonts,
+    };
+}