List of applied suggestions:

• Removed msg calls.
• Removed unused variables. IMPORTANT: For now, I've left unused struct properties to avoid changing the communication interface with the program. My main goal was to apply all suggestions without touching the "tests.rs" file, to ensure the business logic behind the program remained unchanged.
• Broke the code into smaller functions. I've not only moved them to separate functions but also placed the functions in a dedicated module for clarity. Let me know if you are okay with this decision.
• Using invoke_signed without the system program account. Let me know if I understood this particular requirement correctly.
• Replaced panicking asserts with supported Solana Errors. Let me know if the ones I used are okay for you.
• Removed inner scopes where they were not necessary.

Do you want me to prepare unit tests for the functions moved to the /utils directory, or are the already prepared tests sufficient for us at this stage?