Classify llama-server startup failures so diffusion/image GGUFs (FLUX, Qwen-Image, LTX, ERNIE-Image, Z-Image, ...) point users to the Images page instead of a misleading out-of-memory error. Other unknown architectures get a precise unsupported message; Ollama and OOM fallbacks are preserved.
Architecture is matched exactly against general.architecture, covering the arches Unsloth ships as GGUF: flux, qwen_image, ltxv, wan, lumina2.
Fixes#5842.
