feat(library): search a book on Goodreads from the library and reader (#4543) (#4548)

Adds a quick "Search on Goodreads" action so readers can jump straight to
Goodreads to track a book instead of retyping the title there.

- Library: a Goodreads button in the Book Details view (works on web,
  desktop and mobile) searching the book's title + author, plus a
  "Search on Goodreads" item in the desktop right-click context menu.
- Reader: Goodreads is added as a built-in web-search provider so
  highlighted text (e.g. a short-story title inside a magazine) can be
  looked up on Goodreads. Disabled by default like the other built-ins;
  enable it in Settings -> Dictionaries.

Both surfaces are used because the native context menu is desktop-only;
the Book Details button covers web and mobile. Adds a shared
openExternalUrl() helper and translates "Search on Goodreads" across all
locales (the Goodreads brand name is kept verbatim).

Closes #4543

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

apps/readest-app/src/utils/goodreads.ts

@@ -0,0 +1,17 @@
+import { Book } from '@/types/book';
+
+const GOODREADS_SEARCH_URL = 'https://www.goodreads.com/search';
+
+/** Build a Goodreads search URL for an arbitrary query string. */
+export const getGoodreadsSearchUrl = (query: string): string =>
+  `${GOODREADS_SEARCH_URL}?q=${encodeURIComponent(query.trim())}`;
+
+/**
+ * Compose the Goodreads search query for a book from its title and author.
+ * The author improves match precision; it's dropped when empty.
+ */
+export const getBookGoodreadsQuery = (book: Pick<Book, 'title' | 'author'>): string =>
+  [book.title, book.author]
+    .map((part) => part?.trim())
+    .filter(Boolean)
+    .join(' ');

apps/readest-app/src/utils/open.ts

@@ -1,6 +1,20 @@
 import { openUrl } from '@tauri-apps/plugin-opener';
 import { isTauriAppPlatform } from '@/services/environment';
 
+/**
+ * Open an external URL in the system browser. On Tauri the in-app webview
+ * ignores `target="_blank"`, so route through the opener plugin; on web fall
+ * back to `window.open`. Unlike `interceptWindowOpen`, this works without the
+ * reader-scoped `window.open` override being installed.
+ */
+export const openExternalUrl = (url: string) => {
+  if (isTauriAppPlatform()) {
+    void openUrl(url).catch((err) => console.warn('Failed to open external URL', url, err));
+  } else {
+    window.open(url, '_blank', 'noopener,noreferrer');
+  }
+};
+
 export const interceptWindowOpen = () => {
   const windowOpen = window.open;
   globalThis.open = function (