docs(frank-large): resync slots=3 across AGENTS and runbook

Ledger confirms the change landed: "3 slot(s) over one 524288-position pool",
"slots: 1 -> 3 POOLED, 111.0 MiB each", held 103.5 -> 103.4 GiB.

Recorded the oversubscription nuance that the old row missed: the slots were
never the binding constraint on context. 4 x 262144 exceeds the 524288 pool,
so admission was pool-bound all along -- two full-length conversations, or
four at 131k. Lowering the cap trims simultaneous requests, not capacity.

AGENTS.md

@@ -32,7 +32,7 @@ host.
 | Target | Runtime | Service | Model | Port |
 |--------|---------|---------|-------|------|
 | Dankserver | FreeToken v0.1.2 | frank-small | batsclamp Huihui-Qwen3.6-35B-A3B-abliterated-FP8 (block-fp8 e4m3 128x128, ~35 GB safetensors), experts host-RAM LRU, 262144 ctx / 4 concurrent, reasoning on | 7770 |
-|Dankclaw|halogen-flash-server 0.5.8 (rootless Quadlet container)|frank-large|peonist-ai/halogen-qwen3.8-flash-next (Qwen3.8-Flash-Next w4b .hgn 115.55 GiB + quality overlay, ~68 GiB pinned, 262144 ctx / 4 slots, pool 524288 / max_tok 32768 / reserve 15, vision tower on, greedy for silent clients)|7770|
+|Dankclaw|halogen-flash-server 0.5.8 (rootless Quadlet container)|frank-large|peonist-ai/halogen-qwen3.8-flash-next (Qwen3.8-Flash-Next w4b .hgn 115.55 GiB + quality overlay, ~68 GiB pinned, 262144 ctx / 3 slots, pool 524288 / max_tok 32768 / reserve 15, vision tower on, greedy for silent clients)|7770|
 | Dankclaw | *(retired 2026-09-11)* FastFlowLM v1.0.1 on the XDNA2 NPU | frank-npu | Gemma4-E4B-IT-NPU2 pack (vision + audio). Retired with the `amd_iommu=off` decision: the driver's SVA/PASID bind needs an enabled IOMMU | 7771 |
 
 History: the 2026-08-17 redo retired the pipeline-parallel split and the
@@ -397,7 +397,8 @@ with `HALOGEN_MODEL_ID=frank-large`, so no client wiring changed.
 
 Deployed flags: `HALOGEN_CTX=262144`, `HALOGEN_KV_POOL_POSITIONS=524288`
 (**in force** since 2026-09-12 — two full-length conversations resident, or
-four at 131k), `HALOGEN_KV_SLOTS=4`, `HALOGEN_MAX_TOK=32768`,
+four at 131k), `HALOGEN_KV_SLOTS=3` (lowered from 4 on 2026-09-12 to the real
+fleet size; 111 MiB of O(1) state each), `HALOGEN_MAX_TOK=32768`,
 `HALOGEN_HOST_RESERVE_GIB=15`, `HALOGEN_VISION_TOWER=1`, and
 `HALOGEN_DOWNLOAD=peonist-ai/halogen-qwen3.8-flash-next` for the first-start
 fetch; everything else is upstream's default. **Pool and reserve are a matched