vllm: rename stack from vllm-qwen3 → vllm + add Skywork reward classifier

Two related changes shipped together. The stack rename is independent
but adding `vllm-reward` to the existing `vllm-qwen3` would have made
that name actively misleading.

**Rename:** `stacks/vllm-qwen3/ → stacks/vllm/`. Updated all in-repo
references (README.md root, servers/ana-ml2/, stacks/llama-swap/,
configs/restic/ana-ml2/, docs/runbooks/disaster-recovery.md). Two
intentional history mentions retained (servers/ana-ml2 + stacks/vllm
README).

**Add `vllm-reward` service:** serves Skywork-Reward-V2-Llama-3.1-8B-AWQ
on port 8003. The AWQ output is a locally-quantized model (not from HF),
so bind-mounts `/tank/aimodels/llm:/local-models:ro` rather than the
shared HF cache. Model config.json declares LlamaForSequenceClassification
which vLLM's pooling runner picks up automatically — produces a single
reward score per input via /classify.

**Flag note:** the user's spec listed `--task classify`, but vLLM 0.19.1
deprecated --task in favor of --runner pooling (model architecture in
config.json drives the classification head). Compose uses --runner
pooling with a comment explaining the substitution.

**GPU memory:** no rebalance needed — production had already tuned
EMBED/RERANK down from 0.40 to 0.20 each (canonical .env.example now
matches reality). Adding REWARD at 0.30 totals 0.70, leaving ~14 GB
headroom on the 48 GB Ada.

**Server-side:** brought existing vllm-qwen3 down, mv'd
/opt/docker/compose/vllm-qwen3 → /opt/docker/compose/vllm, appended
REWARD_* lines to existing .env (preserving API_KEY/HF_TOKEN), deployed
new compose via scripts/deploy-stack.sh, brought all 3 services up.

**Smoke tests:**
- /health on 8001/8002/8003 → 200
- /v1/models on 8003 → lists Skywork/Skywork-Reward-V2-Llama-3.1-8B-AWQ
  with max_model_len 16384
- /classify with a sample conversation → returns LABEL_0 with prob 0.9999
  (single-output regression-style reward score, expected shape for a
  reward model)

docs/runbooks/disaster-recovery.md

@@ -209,7 +209,7 @@ Essentially **all Anaheim primary services** go offline. Because ana-nas lives h
 
 ### ana-ml2 (bare metal Supermicro, 10.250.50.54, BMC 10.250.250.50)
 
-**Blast radius:** AI inference services (llama-swap, vllm-qwen3). Consumer-facing chat/embedding endpoints fail.
+**Blast radius:** AI inference services (llama-swap, vllm). Consumer-facing chat/embedding/reward-scoring endpoints fail.
 
 **Recovery:**
 1. Check OS via SSH. If unresponsive, BMC console at <https://10.250.250.50>.