fix(recipe): set XDG_CACHE_HOME to /root/.cache for JIT persistence

JIT artifacts land under /root/.cache/jit/ inside the already-mounted
HF cache volume (~/.cache/huggingface), avoiding recompilation on cold
boots.

recipes/glm52-hybrid-fp8-mxfp4/recipe.toml

@@ -108,9 +108,9 @@ CUTE_DSL_ARCH = "sm_121a"
 TORCH_CUDA_ARCH_LIST = "12.1a"
 
 # ── JIT cache ──────────────────────────────────────────────────────────────
-# Uses launcher default: /root/.cache/huggingface
-# Set XDG_CACHE_HOME to override; mount a persistent volume to avoid
-# ~20 min recompilation on each cold boot.
+# Under ~/.cache so it persists inside the HF cache mount (-v ~/.cache/.../hf)
+# Avoids ~20 min recompilation on each cold boot.
+XDG_CACHE_HOME = "/root/.cache"
 
 # ── NCCL overrides ─────────────────────────────────────────────────────────
 # Cluster config provides NCCL_IB_HCA, NCCL_IB_GID_INDEX, NCCL_SOCKET_IFNAME