feat(library): add "Progress Read" sort option (#4427) (#4893)

Sort the library by reading progress (current/total pages). Books that
have never been opened read 0% and sort to the unread end; groups sort
by their most-progressed book. Direction reuses the existing
ascending/descending toggle, so "most read first" is Descending.

Adds the "Progress Read" entry to the Sort by menu and translates it
across all locales.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

apps/readest-app/src/__tests__/app/library/library-utils-extended.test.ts

@@ -195,6 +195,21 @@ describe('getBookSortValue', () => {
     const book = createMockBook({ updatedAt: 99999 });
     expect(getBookSortValue(book, 'unknown' as LibrarySortByType)).toBe(99999);
   });
+
+  it('should return read ratio for Progress sort', () => {
+    const book = createMockBook({ progress: [50, 100] });
+    expect(getBookSortValue(book, LibrarySortByType.Progress)).toBe(0.5);
+  });
+
+  it('should return 0 for Progress sort when book has no progress', () => {
+    const book = createMockBook({});
+    expect(getBookSortValue(book, LibrarySortByType.Progress)).toBe(0);
+  });
+
+  it('should return 0 for Progress sort when total pages is 0', () => {
+    const book = createMockBook({ progress: [0, 0] });
+    expect(getBookSortValue(book, LibrarySortByType.Progress)).toBe(0);
+  });
 });
 
 describe('compareSortValues', () => {
@@ -310,4 +325,21 @@ describe('createBookSorter - additional cases', () => {
     expect(sorted[0]!.title).toBe('Older');
     expect(sorted[1]!.title).toBe('Newer');
   });
+
+  it('should sort by reading progress ascending (unread books first)', () => {
+    const books = [
+      createMockBook({ title: 'Almost done', progress: [90, 100] }),
+      createMockBook({ title: 'Not started' }),
+      createMockBook({ title: 'Just begun', progress: [10, 100] }),
+      createMockBook({ title: 'Halfway', progress: [1, 2] }),
+    ];
+    const sorter = createBookSorter(LibrarySortByType.Progress, 'en');
+    const sorted = [...books].sort(sorter);
+    expect(sorted.map((b) => b.title)).toEqual([
+      'Not started',
+      'Just begun',
+      'Halfway',
+      'Almost done',
+    ]);
+  });
 });

apps/readest-app/src/__tests__/utils/library-utils.test.ts

@@ -544,6 +544,18 @@ describe('getGroupSortValue', () => {
     expect(getGroupSortValue(group, LibrarySortByType.Series)).toBe('My Series');
   });
 
+  it('should return max read ratio for progress sort', () => {
+    const group = createMockGroup({
+      books: [
+        createMockBook({ progress: [10, 100] }),
+        createMockBook({ progress: [80, 100] }),
+        createMockBook({}),
+      ],
+    });
+
+    expect(getGroupSortValue(group, LibrarySortByType.Progress)).toBe(0.8);
+  });
+
   it('should handle empty groups gracefully', () => {
     const group = createMockGroup({ books: [] });