Add Save States to Your Emulator

Implement save state serialization for a simple emulator in C.

Requirements:

• Define a SaveState struct containing CPU state, memory, timers, and display state
• Implement save_state_to_file() that writes the SaveState struct to a binary file
• Implement load_state_from_file() that reads the file and validates a magic header
• Implement dump_state_text() that prints a human-readable summary of all state fields
• Implement restore_state() that copies a SaveState back into the running emulator
• Include a version field and ROM checksum in the save state header
• Write a test program that creates an emulator, runs a few cycles, saves state, modifies state, then restores and verifies
• Print before/after comparisons showing that restoration was successful