doc: comments for codebase and updated documentation

src/features/GetFonts/lib/filterManager/filterManager.svelte.ts

@@ -4,6 +4,11 @@ import type { FilterConfig } from '../../model';
 
 /**
  * Create a filter manager instance.
+ * - Uses debounce to update search query for better performance.
+ * - Manages filter instances for each group.
+ *
+ * @param config - Configuration for the filter manager.
+ * @returns - An instance of the filter manager.
  */
 export function createFilterManager<TValue extends string>(config: FilterConfig<TValue>) {
     const search = createDebouncedState(config.queryValue ?? '');

src/features/GetFonts/lib/mapper/mapManagerToParams.ts

@@ -1,6 +1,12 @@
 import type { FontshareParams } from '$entities/Font';
 import type { FilterManager } from '../filterManager/filterManager.svelte';
 
+/**
+ * Maps filter manager to fontshare params.
+ *
+ * @param manager - Filter manager instance.
+ * @returns - Partial fontshare params.
+ */
 export function mapManagerToParams(manager: FilterManager): Partial<FontshareParams> {
     return {
         q: manager.debouncedQueryValue,