Implement a Game Boy Emulator: Sharp LR35902 CPU and GPU

Implement Game Boy CPU core and LCD controller concepts in C.

Requirements:

• Define a GameBoy struct with CPU registers (A, F, B, C, D, E, H, L, SP, PC), memory array, and LCD state
• Implement memory read/write functions that handle ROM banking (simulate MBC1 with one switchable bank)
• Implement a fetch-decode-execute loop for LR35902 opcodes: LD, ADD, SUB, JP, CALL, RET
• Implement a function that prints the current CPU state including all registers and flags
• Define LCD structs for background tiles, window, and sprites
• Implement a function that prints an 8x8 tile from VRAM as ASCII art
• Implement a function that prints the LCD mode cycle (HBlank, VBlank, OAM, Transfer)
• Load a minimal test program and run at least 5 cycles, printing state each time