feat(fv-ml1): rebalance GPUs 0/1 by usage; contexts to published maximums; gen-small default output cap

Layout: GPU 0 = cyberprev (KV 16 -> 15 GiB, 1.29x), erp-seat (moved from
GPU 1, KV 8.49 -> 5.5 GiB, 1.32x), voices (ctx 8,192 -> 40,960, its native
maximum, KV 6 GiB, 1.07x), coder (moved from GPU 1, ctx 16,384 -> 32,768,
the card maximum, 2.35x), parakeet-nemo. GPU 1 = gen-small (moved from
GPU 0, 5.5 GiB, 1.76x), meromero-rp (22 GiB, 1.32x), intern-decision.

Sizing rule: KV >= 1.25x max context rounded up to 0.5 GiB, checked against
7 days of LiteLLM traffic and the engines' own KV-usage logs. Each card keeps
spare memory for its bursty tenant (parakeet's cap on GPU 0, intern-decision's
32k call on GPU 1). YaRN extensions are not enabled: they do not fit, and the
Qwen cards warn static YaRN degrades short prompts.

gen-small gets --override-generation-config max_new_tokens 32768. It applies
only to requests that omit max_tokens (vLLM get_max_tokens) and answers 9
runaway ~260k-token replies in 7 days; the longest normal reply was 6,357.

Applied with playbooks/fv-ml1-rebalance-20261005.yaml (boot-check guard and
health/KV verification per seat); all nine seats healthy, gateway smoke
tests pass.

stacks/voices-seat/README.md

@@ -69,7 +69,13 @@ separately.
 
 ## Placement warnings
 
-⚠ **GPU 0 is now at 96.0 of 97.9 GB.** This seat's 10.7 GB went into the last real gap on
+> **2026-10-05 rebalance:** context raised 8,192 → **40,960** (Qwen3-4B's native maximum: the card's 32,768
+> plus its 8,192 prompt reserve; 131,072 would need YaRN, which the card says hurts short prompts). KV pinned
+> 6 GiB bf16 = 43,680 tokens (1.07×), util 0.16, resident ~15.4 GB. Still GPU 0, now beside cyberprev,
+> erp-seat, coder and parakeet-nemo. The LoRA voices were trained on short prose; long-context behaviour
+> with an adapter is unmeasured.
+
+⚠ *(historical, pre-2026-10-05)* **GPU 0 is now at 96.0 of 97.9 GB.** This seat's 10.7 GB went into the last real gap on
 fv-ml1: GPU 1 has ~5.7 GB, GPU 2 has ~2.4 GB, and GPU 3 is a held reserve for a future
 full-card seat (`flash-next` alone needs 93 of 96 GiB). **There is no room for another seat
 here without a placement decision.**

stacks/voices-seat/compose.yaml

@@ -87,11 +87,11 @@ services:
       - --port
       - "8000"
       - --gpu-memory-utilization
-      - "${VOICES_GPU_MEM_UTIL:-0.12}"
+      - "${VOICES_GPU_MEM_UTIL:-0.16}"
       - --kv-cache-memory
-      - "${VOICES_KV_CACHE_MEMORY:-2147483648}"
+      - "${VOICES_KV_CACHE_MEMORY:-6442450944}"
       - --max-model-len
-      - "${VOICES_MAX_MODEL_LEN:-8192}"
+      - "${VOICES_MAX_MODEL_LEN:-40960}"
       - --max-num-seqs
       - "${VOICES_MAX_NUM_SEQS:-8}"
       - --dtype