feat: allow removing book from recent list (#2045)

## Summary

Add ability to long press 'confirm' on a book in the recent books list
to be prompted to remove it from the list.

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### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.

Did you use AI tools to help write this code? *Yes, Claude*

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src/RecentBooksStore.h

@@ -37,7 +37,7 @@ class RecentBooksStore {
   void updateBook(const std::string& path, const std::string& title, const std::string& author,
                   const std::string& coverBmpPath);
 
-  // Remove the entry whose path matches (used when a book is finished/read).
+  // Remove the entry whose path matches (used when a book is removed from recents or finished/read).
   // Returns true if an entry was found and removed (no-op + false otherwise).
   // Persistence is best-effort: a failed save is logged, not reflected in the return.
   bool removeByPath(const std::string& path);