feat(vllm): replace phi4-mini with Granite 4.1 8B summarizer + retune GPU 1

Granite 4.1 8B beat phi4-mini on precision in brokkr's R15 P03 eval, so it's
the new production summarizer/dreamer for nevermore.

- vllm-phi4 -> vllm-granite: official IBM FP8 (ibm-granite/granite-4.1-8b-fp8,
  compressed-tensors), GPU 1, 50K ctx, FP8-KV, CUDA graphs. Same :8004 slot.
- GPU 1 retune: the embed/rerank/reward trio was over-provisioned (embed ran a
  5.89x KV pool, reward 3.90x). Trimmed utils 0.20/0.20/0.30 -> 0.07/0.07/0.18,
  freeing ~10 GB so granite runs with CUDA graphs (not --enforce-eager) and
  keeps ~10 GB free as a hedge for future Granite text-LoRAs (--enable-lora).
- LiteLLM: phi4-mini model_list entry -> granite-4.1-8b (hosted_vllm @ :8004);
  explicit entry shadows the '*' wildcard's llama-swap route.
- nevermore repointed (LLAMA_SWAP_MODEL=granite-4.1-8b via the gateway) live.

Verified end-to-end: vLLM :8004 generates, gateway routes (gateway-granite-ok),
KV 86,768 tokens/1.69x at 50K, 0 restarts, GPU 1 10.3 GB free.

stacks/litellm/conf/config.yaml

@@ -17,11 +17,14 @@
 # route — left direct; see README.
 
 model_list:
-  # --- Phi-4-mini (generative chat) — production summarizer + dreaming
-  #     agent. Full prompt + completion captured per call. ---
-  - model_name: phi4-mini
+  # --- Granite 4.1 8B (generative chat) — production summarizer + dreaming
+  #     agent. Replaced phi4-mini 2026-06-05 (beat it on precision in brokkr's
+  #     R15 P03 eval). vLLM on ana-ml2 GPU 1, official FP8, 50K ctx. Explicit
+  #     entry shadows the "*" wildcard's llama-swap route for this name. Full
+  #     prompt + completion captured per call. ---
+  - model_name: granite-4.1-8b
     litellm_params:
-      model: hosted_vllm/phi4-mini
+      model: hosted_vllm/granite-4.1-8b
       api_base: http://10.250.50.54:8004/v1
       api_key: os.environ/VLLM_API_KEY
     model_info: