Add memory tracing and scanning debugger commands

[lusca0x01]

This PR adds new debugger commands for memory analysis, useful for ROM debugging and reverse engineering.

New Commands

Memory Tracing:

• read <address> - Read and display a single memory address
• trace_read - Toggle logging of all memory reads
• trace_write - Toggle logging of all memory writes
• trace_clear - Clear the trace buffers
• trace_dump <filename> - Dump traced memory to a file

Memory Scanning (CheatEngine-like):

• scan all - Initialize scan with all addresses
• scan exact <value> - Filter addresses matching exact value
• scan changed - Filter addresses whose value changed since last scan
• scan unchanged - Filter addresses whose value remained the same
• scan_dump <filename> - Export scan results to file
• scan_clear - Reset scan state

Use Cases

• Debugging homebrew ROMs
• Finding memory addresses for specific game values (lives, score, etc.)
• Tracing memory access patterns during execution
• Reverse engineering ROM behavior

Implementation

• Added trace and scan state fields to GB_gameboy_t (guarded by GB_DISABLE_DEBUGGER)
• Memory tracing hooks in GB_read_memory and GB_write_memory
• All new commands follow existing debugger command patterns

Inspired by LiveOverflow's Game Boy hacking videos.

[ISSOtm]

This kind of functionality looks very interesting, but I'm not sure what the intended syntax for the new commands' arguments is? Like, what kind of range syntaxes are supported, etc.

[lusca0x01]

I've updated the command help strings to clarify the syntax!
Let me know if you'd prefer a different format or if the documentation still needs adjustment!