fix: Dolphin save states crash the emulation worker (segfault in retro_serialize)

[ryanmagoon]

Problem

Save states crash the emulation utility process when using the Dolphin (GameCube) libretro core. The worker terminates with a segfault during retro_serialize(), killing the entire emulation session.

Root Cause (confirmed via instrumentation)

The crash is inside Dolphin's retro_serialize() implementation — not in our GL setup or buffer allocation. Diagnostic logging confirms:

[gamelord] serialize: calling retro_serialize_size...
[gamelord] serialize: size=92409028 (88.1MB)
[gamelord] serialize: allocating 92409028 bytes...
[gamelord] serialize: calling retro_serialize...
[error] [ (ipc) ] Failed to save state: Error: Worker process terminated

We verified:

• ✅ GL context is current (CGLSetCurrentContext)
• ✅ FBOs are unbound (glBindFramebuffer(GL_FRAMEBUFFER, 0))
• ✅ GL pipeline is flushed (glFinish())
• ✅ Accumulated GL errors are drained
• ✅ 88MB buffer allocation succeeds
• ❌ retro_serialize() segfaults inside Dolphin's own code

The initial GL_INVALID_FRAMEBUFFER_OPERATION (0x0506) error was a red herring — draining it and unbinding FBOs didn't prevent the crash.

Current Mitigation

• Save state UI is hidden for HW-render cores (saveStatesSupported flag piped from worker → renderer)
• Worker-side guard blocks serialize/unserialize as defense-in-depth
• No crash, no broken buttons — users simply don't see save state controls for GameCube

To Fix Properly

Investigate Dolphin's libretro retro_serialize implementation:

• The crash is likely in GPU state serialization (texture cache, shader cache, or framebuffer readback)
• May be specific to CGL offscreen contexts (no window backing)
• May be specific to Apple Silicon / macOS OpenGL 4.1
• Compare with how RetroArch sets up the GL context for Dolphin on macOS
• Contribute fix upstream to libretro/dolphin