idea: Mac AMD Radeon support

[hiro-v]

Problem

• Context: https://discord.com/channels/1107178041848909847/1222681742712897609
• User with old mac want to use Jan with AMD Radeon GPU, however the current vulkan does not support it

Success Criteria

• Just work, we can ask user to test

Additional context

• Link to feat: Support for Nitro with llama.cpp vulkan backend on Mac cortex.cpp#476