feat(locations): remember last Add-window directory

Remember manually selected Add-window folders during the current session, with a persisted Locations toggle and cross-platform path handling.\n\nRefs #23

src/utils/downloadLocations.test.ts

@@ -14,6 +14,7 @@ import {
   formatDerivedCategoryPath,
   normalizeCategorySubfolder,
   normalizeDownloadLocationSettings,
+  resolveInitialAddWindowLocation,
   resolveCategoryDestination,
   subfolderFromDerivedCategoryPath
 } from './downloadLocations';
@@ -24,6 +25,25 @@ describe('download locations', () => {
     expect(downloadLocationEquals('/Users/Test', 'Movie.MP4', '/users/test', 'movie.mp4', 'macos')).toBe(false);
     expect(downloadLocationEquals('/home/Test', 'Movie.MP4', '/home/test', 'movie.mp4', 'linux')).toBe(false);
   });
+
+  it('uses a remembered Add-window directory only when the setting is enabled', () => {
+    expect(resolveInitialAddWindowLocation(
+      'D:\\Downloads',
+      true,
+      'D:\\Course_Videos'
+    )).toEqual({ path: 'D:\\Course_Videos', isManual: true });
+
+    expect(resolveInitialAddWindowLocation(
+      'D:\\Downloads',
+      false,
+      'D:\\Course_Videos'
+    )).toEqual({ path: 'D:\\Downloads', isManual: false });
+  });
+
+  it('falls back to the normalized base folder when no directory was remembered', () => {
+    expect(resolveInitialAddWindowLocation('  ', true, null))
+      .toEqual({ path: '~/Downloads', isManual: false });
+  });
   beforeEach(() => {
     vi.clearAllMocks();
   });

src/utils/downloadLocations.ts

@@ -48,6 +48,26 @@ interface LegacyDownloadLocationSettings {
   downloadDirectories?: unknown;
 }
 
+export interface AddWindowLocationSuggestion {
+  path: string;
+  isManual: boolean;
+}
+
+export const resolveInitialAddWindowLocation = (
+  baseDownloadFolder: string,
+  rememberLastUsedDownloadDirectory: boolean,
+  lastUsedDownloadDirectory: string | null
+): AddWindowLocationSuggestion => {
+  const rememberedPath = rememberLastUsedDownloadDirectory
+    ? lastUsedDownloadDirectory?.trim()
+    : undefined;
+  const basePath = baseDownloadFolder.trim() || '~/Downloads';
+  return {
+    path: rememberedPath || basePath,
+    isManual: Boolean(rememberedPath)
+  };
+};
+
 const stringRecord = (value: unknown): Record<string, string> => {
   if (!value || typeof value !== 'object') return {};
   return Object.fromEntries(