frank-default-small: lower context by 32k per stream for cache headroom

3 slots x 229376 (262144 - 32768) = 688128 total context. Updates the
.env, models.json (contextWindow/maxTokens 229376 per slot), and the
index/deployment/ornith runbook references.

docs/LLM/deployment.md

@@ -128,7 +128,8 @@ binary with the MoE expert weights pinned to CPU by an explicit
 `--override-tensor` regex (the expert `\.ffn_(up|down|gate|gate_up)_(ch|)exps`
 pattern, buffer type `CPU`) and 7 CPU threads, native `draft-mtp`
 speculative decoding (bundled MoE MTP head, n_max 4), f16 KV, context
-786432 (3 slots of ~262K each), batch 4096 / ubatch 2048, `--no-mmap`. The
+688128 (3 slots of ~229K each, 32k headroom per stream), batch 4096 /
+ubatch 2048, `--no-mmap`. The
 unit is `scripts/frank-default-small.service`. It launches through
 `scripts/serve-frank-small.sh`, which reads tunables from
 `scripts/frank-default-small.env`. See [[dealign-ornith-crack]].