v0.30.0-rc32: llama-server followups (#16353)

• llama-server followups

Misc fixes for #16031

• Add back dropped ROCm build flag for multi-GPU support on windows
• Fix amdhip64_*.dll version detection for "latest" selection
• Fix embeddings API for consistent normalize behavior with prior versions

• ci: set up for automated llama.cpp update testing

• reduce batch for fa-disabled, and constrained vram

• mlx: fix v3 load bug on m5

Imagegen was incorrectly loading v3 first. This DRYs out the loading code so imagegen gets the same new v4/v3 selection logic.

• fix reload bug on embedding models

• bump version

• steer user how to enable iGPU when disabled