Add IOP, audio, pad, fio changes, VAG handling, and call-stack logger

[aslanhudajev]

• Add IOP with RPC handling (handleRPC, LibSd SID) and init/reset using RDRAM
• Add IOP audio layer for LibSd RPC (handleLibSdRpc)
• Add PS2AudioBackend with VAG decode, onVagTransfer/onSoundCommand, raylib playback
• Add PSPadBackend with readState and raylib input
• Add IOP RAM mapping in Memory (getIOPRAM) for EE↔IOP access
• Add fio syscalls: fioOpen, fioRead, fioWrite, fioClose, fioLseek, fioMkdir
• Add VAG accumulation for fio reads (multi-chunk VagAccumEntry)
• Add ps2_log.h call-stack logger (tab-indented, Debug only, ps2_log.txt next to exe)
• Code generator: emit ps2_log include and PS_LOG_ENTRY for full functions
• Recompiler: emit ps2_log include and PS_LOG_ENTRY for stubs
• Runtime: print "[PS2 LOG] Logs saved at " on exit (Debug only)

Architecture

flowchart TB
    subgraph EE["Emotion Engine (EE)"]
        Recomp["Recompiled Code"]
        Syscalls["Syscalls / Stubs"]
    end

    subgraph Memory["Memory"]
        RDRAM["RDRAM (EE main RAM)"]
        IOPRAM["iop_ram (future)"]
    end

    subgraph IOP["IOP Layer"]
        RPC["handleRPC()"]
        LibSd["LibSd RPC"]
    end

    subgraph Backends["Host Backends"]
        Audio["PS2AudioBackend\n(VAG decode, raylib)"]
        Pad["PSPadBackend\n(raylib input)"]
    end

    subgraph FIO["File I/O"]
        SyscallFio["fioOpen/Read/Write/Close/Lseek/Mkdir"]
        VagAccum["VAG accumulation\n(multi-chunk)"]
        HostFS["Host filesystem"]
    end

    Recomp --> Syscalls
    Syscalls -->|"SIF RPC"| RPC
    Syscalls -->|"pad reads"| Pad
    Syscalls --> SyscallFio

    RPC -->|"rdram ptr"| RDRAM
    RPC --> LibSd
    LibSd --> Audio

    SyscallFio --> VagAccum
    VagAccum --> HostFS
    VagAccum -->|"VAG data"| Audio

    RDRAM -.->|"not yet used"| IOPRAM
    ```

Loading

[aslanhudajev]

Note how the audio implementation does not yet use iop_ram from ps2_memory.h.
Just wanted to make that clear.

[aslanhudajev]

Problems:
When any input is read, audio slows down considerably.
Will need to be fixed in future release.