feat: add long-press Confirm for book management in file browser and recents

Long-pressing Confirm on a book file in MyLibraryActivity or
RecentBooksActivity opens the BookManageMenuActivity popup with
Archive/Delete/Delete Cache/Reindex options. Actions are executed
via BookManager and the file list is refreshed afterward.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/activities/home/MyLibraryActivity.h

@@ -17,6 +17,10 @@ class MyLibraryActivity final : public ActivityWithSubactivity {
   std::string basepath = "/";
   std::vector<std::string> files;
 
+  // Long-press state
+  bool ignoreNextConfirmRelease = false;
+  static constexpr unsigned long LONG_PRESS_MS = 700;
+
   // Callbacks
   const std::function<void(const std::string& path)> onSelectBook;
   const std::function<void()> onGoHome;
@@ -25,6 +29,8 @@ class MyLibraryActivity final : public ActivityWithSubactivity {
   void loadFiles();
   size_t findEntry(const std::string& name) const;
 
+  void openManageMenu(const std::string& bookPath);
+
  public:
   explicit MyLibraryActivity(GfxRenderer& renderer, MappedInputManager& mappedInput,
                              const std::function<void()>& onGoHome,