fix(search): link results to book detail page and add cover thumbnails

Search results navigated to /bookshelf with no filters instead of the
selected book's page. Results now link to /media/:id and display cover
thumbnails, with cover URLs resolved server-side via ResolveMediaURL.
Removes the dead selectedBook localStorage plumbing.

web/src/storage.ts

@@ -45,14 +45,6 @@ function setSelectedLibrary(libraryId: string): void {
   document.cookie = `selectedLibrary=${encodeURIComponent(value)};path=/;max-age=${365 * 24 * 60 * 60};samesite=lax`;
 }
 
-function getSelectedBook(): string | null {
-  return localStorage.getItem("selectedBook");
-}
-
-function setSelectedBook(bookId: string): void {
-  localStorage.setItem("selectedBook", bookId);
-}
-
 function clearAll(): void {
   localStorage.clear();
 }
@@ -61,14 +53,12 @@ export {
   ALL_LIBRARIES,
   clearAll,
   getRefreshToken,
-  getSelectedBook,
   getSelectedLibrary,
   getTheme,
   getToken,
   removeRefreshToken,
   removeToken,
   setRefreshToken,
-  setSelectedBook,
   setSelectedLibrary,
   setTheme,
   setToken