refactor: create separate BLoCs for each screen with comprehensive tests

- Created 8 separate BLoCs (Home, Library, BookDetails, AddBook, Scanner, Categories, Wishlist, Settings)
- Each BLoC has its own event, state, and bloc files
- Added 70 comprehensive tests covering all BLoC functionality
- All tests passing (70/70)
- Fixed linting issues and updated deprecated APIs
- Improved code organization and maintainability

bookshelf_flutter/windows/runner/utils.h

@@ -0,0 +1,19 @@
+#ifndef RUNNER_UTILS_H_
+#define RUNNER_UTILS_H_
+
+#include <string>
+#include <vector>
+
+// Creates a console for the process, and redirects stdout and stderr to
+// it for both the runner and the Flutter library.
+void CreateAndAttachConsole();
+
+// Takes a null-terminated wchar_t* encoded in UTF-16 and returns a std::string
+// encoded in UTF-8. Returns an empty std::string on failure.
+std::string Utf8FromUtf16(const wchar_t* utf16_string);
+
+// Gets the command line arguments passed in as a std::vector<std::string>,
+// encoded in UTF-8. Returns an empty std::vector<std::string> on failure.
+std::vector<std::string> GetCommandLineArguments();
+
+#endif  // RUNNER_UTILS_H_